Bug: OAuth 2.0 State Parameter fails with Pipe Delimiters (RFC 6749 Non-Compliance)

Bug: OAuth 2.0 State Parameter fails with Pipe Delimiters (RFC 6749 Non-Compliance)

I've discovered a bug in how Zoho's API Console handles the OAuth 2.0 authorization flow when the state parameter contains pipe characters (|), and I'm hoping the Zoho team can address this in a future update.
The Issue
Zoho's OAuth 2.0 implementation for server-based client applications uses the standard authorization endpoint:
https://accounts.zoho.com/oauth/v2/auth?response_type=code
&client_id=<client_id>
&scope=<scope>
&redirect_uri=<redirect_uri>
&access_type=offline
&state=<state_value>
While Zoho's documentation does not explicitly list the state parameter, it is a standard part of the OAuth 2.0 specification (RFC 6749 Section 4.1.1) and is widely used for CSRF protection and maintaining application state through the authorization flow.
However, when the state parameter contains pipe characters (|), Zoho's authorization server fails to process the request correctly, preventing users from authorizing the connection. This occurs whether the pipe characters are URL-encoded (%7C) or left unencoded.
The Problem
The pipe character is a standard delimiter in multi-part state values, particularly when passing a combination of a CSRF token and a return URL. This behavior—failing on both encoded and unencoded pipe characters—is often indicative of overly restrictive input validation or a "leaky" WAF/Proxy layer that decodes parameters before the application logic can handle them.
State Value As Sent in URL Result
abc123xyz state=abc123xyz ✓ Works correctly
session_12345 state=session_12345 ✓ Works correctly
user|action|timestamp state=user|action|timestamp
(unencoded pipes)
✗ Authorization fails
user|action|timestamp state=user%7Caction%7Ctimestamp
(URL-encoded pipes)
✗ Authorization fails
user:action:timestamp state=user%3Aaction%3Atimestamp ? Not tested
Note: Pipe characters cause failures whether URL-encoded or not. Other special characters/delimiters have not been tested and may or may not exhibit similar issues.
RFC 6749 Compliance Issue
Section 4.1.1 - Authorization Request:
"state: RECOMMENDED. An opaque value used by the client to maintain state between the request and callback."
Section 4.1.2 - Authorization Response:
"state: REQUIRED if the 'state' parameter was present in the client authorization request. The exact value received from the client."
The RFC explicitly defines the state parameter as an opaque value. This means:
  • The Authorization Server should not be looking "inside" or parsing the string at all
  • The state value must pass through the authorization process unchanged
  • Any URL-encoded characters should be handled transparently
  • The exact value received must be returned to the client in the redirect
Key Point: By definition, an "opaque" parameter means the authorization server must treat it as a data blob—accepting it, storing it, and returning it without any interpretation or transformation.
Current Behavior vs Expected Behavior
Current Behavior Expected Behavior (Per RFC 6749)
1. Client sends: state=user|action|123
(or state=user%7Caction%7C123)
2. Zoho fails to parse the state parameter
3. Authorization server returns HTTP 400 Bad Request
4. User cannot authorize the connection
1. Client sends: state=user|action|123

2. Zoho treats state as opaque data blob
3. User authorizes the connection
4. Redirect includes the exact value received:
state=user|action|123
(or consistently encoded as sent)
The Current Workaround (Suboptimal)
Important: The workarounds below only apply if you have control over the client application generating the OAuth request. If you're integrating with a third-party application that sets the state parameter (e.g., integration platforms, SaaS tools, enterprise software), you have no ability to modify the state value and therefore no workaround is available. You are completely blocked from completing the OAuth flow.
For developers who do control the client application, you must avoid pipe characters entirely:
// Instead of using pipes as delimiters:
state = csrf_token + "|" + user_id + "|" + redirect_path;
// ❌ This breaks Zoho's authorization flow

// Developers must use alternative approaches:
state = csrf_token + "_SEP_" + user_id + "_SEP_" + redirect_path;
// or
state = base64_encode(json_encode({"csrf": token, "user": id, "path": path}));
// or
state = csrf_token; // Store other data server-side keyed by CSRF token
Problems with these workarounds:
  • Requires refactoring existing codebases that use pipe delimiters
  • Base64 encoding increases state parameter length significantly, risking URL length limits (particularly in older browsers and some enterprise proxies which enforce ~2000 character limits)
  • Server-side storage approach adds complexity, database overhead, and potential race conditions
  • Inconsistent with how the same code works with other OAuth providers (Google, Microsoft, etc.)
  • Developers may not discover this issue until production deployment
  • Custom delimiters (like _SEP_) are non-standard and may conflict with actual data values
What Should Happen Instead
Proposed Solution:
Zoho's authorization server should properly handle URL-encoded pipe characters (%7C) in the state parameter, as required by RFC 6749. The state value must be treated as an opaque data blob.
Technical Requirement: Treat state as a Data Blob
1. Input Accept %7C (and other encoded characters) as valid parts of the query string without triggering validation errors or WAF rules
2. Persistence Store the string exactly as received during the user's login/consent session—do not decode, parse, or transform
3. Output Append the exact string back to the redirect_uri without additional transformations that might strip or corrupt the delimiters
This approach:
  • Complies with RFC 6749's requirement to return "the exact value received"
  • Follows the same behavior as other major OAuth providers
  • Requires no changes from client applications
  • Unblocks third-party integrations that cannot modify their state format
Real-World Impact
This limitation affects any integration where:
  • Third-party applications set the state parameter and cannot be modified (integration platforms, SaaS connectors, enterprise software)
  • Multi-tenant applications need to encode tenant ID and return URL in state
  • CSRF protection implementations combine security tokens with application state
  • Single Sign-On flows need to preserve original request context
  • Migration projects from other OAuth providers that used pipe delimiters

Critical Blocker: When the state parameter originates from a third-party system outside your control, there is no workaround available. The integration is completely impossible until this is fixed.

Security Note: The state parameter is critical for CSRF protection in OAuth flows. Forcing developers to change their state encoding approach may inadvertently introduce security vulnerabilities if not handled carefully.

Request to Zoho Team

Can this be addressed in a future update?

This is a standards compliance issue that impacts developers integrating with Zoho's API. For those who control their client application, the current implementation forces unnecessary workarounds. For those integrating third-party applications, the situation is worse:

1. Custom development
Refactor code to avoid pipe characters, creating Zoho-specific OAuth handling
2. Third-party integrations
No workaround possible - integration is completely blocked

Users should not be blocked from integrating with Zoho due to non-standard OAuth implementation.

Community Input Requested: Has anyone else encountered this issue? Are there other special characters that cause similar problems with Zoho's OAuth implementation?

    • Sticky Posts

    • Deprecation of SMS-based multi-factor authentication (MFA) mode

      Overview of SMS-based OTP MFA mode The SMS-based OTP MFA method involves the delivery of a one-time password to a user's mobile phone via SMS. The user receives the OTP on their mobile phone and enters it to sign into their account. SMS-based OTPs offer
    • Recent Topics

    • Es posible cambiar el lenguaje de los modulos del ASAP?

      Es posible cambiar el lenguaje de estos textos? Tengo Zoho configurado en español pero aun así me muestra estos textos en ingles:
    • Where do I edit the "Welcome to [portal name]" message

      I am looking for a way to edit the "Welcome to" part of the message that is seen on the landing page (ex: https://help.zoho.com/portal/en/home). When I use the French interface, it doesn't make sense... I want to change it from "Bienvenue chez" to" Bienvenue au". Thanks!
    • Frustrated with Zoho Assist QuickSUpport

      Trialling Zoho Assist and I have a variety of clients. A lot are computer illiterate. Some have poor vision. The current support sessions are using apps which have desktop icons for the appropriate apps. I either connect on demand then the client approves
    • Zoho ERP | Product updates | July 2026

      Hello users, We're back with another round of updates to help you streamline your operations. This month's release brings new features and enhancements designed to help you work more efficiently. Read on to discover everything that's new in Zoho ERP this
    • Automate Backups

      This is a feature request. Consider adding an auto backup feature. Where when you turn it on, it will auto backup on the 15-day schedule. For additional consideration, allow for the export of module data via API calls. Thank you for your consideration.
    • Shared Snippets Everyone

      Hi, Now that the Shared Snippets have been released and I think will be the most used feature implemented in 2023 :) Creating and Using Snippets in Ticket Responses - Online Help | Zoho Desk Maintain consistency in ticket responses with shared snippets
    • Multi-currency and Products

      One of the main reasons I have gone down the Zoho route is because I need multi-currency support. However, I find that products can only be priced in the home currency, We sell to the US and UK. However, we maintain different price lists for each. There
    • Horrible download speed

      Using a trial of Zoho Assist and downloading a 316 MB file on a 500/500 fibre connection to a remote computer on the same network took 7 mins to complete. On AnyDesk it took 1 min or so.
    • Remove "Subject" as a required field on quotations

      Not sure why, but Zoho has made 'Subject' a system defined required field. I'm not entirely sure why subject would be required as a key field (i.e. you cannot deactivate it or change it from required). It doesn't make much sense on many product quotations,
    • Displaying only unread tickets in ticket view

      Hello, I was wondering if someone might be able to help me with this one. We use filters to display our ticket list, typically using a saved filter which displays the tickets which are overdue or due today. What I'd really like is another filter that
    • Best way to setup Inventory bin tracking for products with multiple boxes/crates

      Hi - we need some advice from the community on setting up Items in the Inventory for products with multiple crates. We have large products in our warehouse where the product is delivered as two large (double pallet) crates. We've setup the Items for these
    • Zoho Books | Product updates | August 2026

      Hello users, July has been an exciting month for Zoho Books! This month, we're excited to introduce HTML PDF Templates, Placeholders as Pills, expanded approval workflows for Sales Returns and Journals, and significant compliance updates across the India,
    • Tip #83- Give Customers a Faster Way to Reach You with the Quick Support Plugin – 'Insider Insights'

      Hello Zoho Assist Community! Think about the last time a customer needed urgent support. They emailed in, waited for a response, got a session link, couldn't find it in their inbox, called back, and by the time the session actually started, a good chunk
    • Can't find field from ZCRM for a trigger

      Hello, Currently I am revamping our CRM system and we have created second layouts from to try out new processes while not disrupting the old one. Moreover, we want to use different layouts for different processes. The issue is that when creating the ZCRM
    • Discount Per Item / Option Removed

      Hi, I was using Zoho Books for three years now and very saticfied. Now, as we try to add an invoice, we founds that the discount option per item was takn away, and a discount from total was implemented. However, we have cases when we add a diffrent discount to each item. Was this option removed permanently? Thanks, 
    • Any Possible to change the challan type in Delivery challan ?

      Hello Team, We need to add the more values in challan type in delivery challan module in Zoho Books.So how to add additional values in challan type field. Please find following snap for your reference. Thanks in Advance, Thisai Moorthy.
    • Show when an invoice has been viewed

      It would be nice to know if/when a customer has viewed an invoice. This would mean not having PDF attachments and just have the link to the invoice. My previous invoicing solution had this feature and I did not realize how much I used it until it was gone. Would this be possible, or this already available and I am just missing it?
    • Customer image field

      I created a custom image field for estimates, and it works as expected. The only issue I have is that I want to be able to place the custom image field in the estimate invoice. Is there a way I can do that, the field does not give the option to display
    • Zoho Books | Product updates | March 2026

      Hello users, We’ve rolled out new features and enhancements in Zoho Books. From Advanced Reporting Tags to the ability to mark projects as completed, explore the latest updates designed to improve your bookkeeping experience. Introducing Advanced Reporting
    • Separator line

      Is there a way i can insert a line in an invoice or quote without showing qty or prices? e.g. Options I Item description qty and price Option II Item description qty and price Thanks
    • All new Address Field in Zoho CRM: maintain structured and accurate address inputs

      Availability Update: 29 September 2025: It's currently available for all new sign-ups and for existing Zoho CRM orgs which are in the Professional edition exclusively for IN DC users. 2 March 2026: Available to users in all DCs except US and EU DC. 24
    • BCC Drop Box Centralisation

      Hi Team, For the last few years, I have had a question related to the Zoho CRM BCC Dropbox feature. Although BCC Dropbox is very useful for tracking customer email communication, I have always wondered why its configuration is managed at the individual
    • Kiosk Page Refresh

      We have a Kiosk running from a button in contacts to update values and also add related lists, which works great, but when the kiosk is finished the page does not refresh to show the changes. Is there a way to force the contact to refresh/update when
    • CRM Integration - Option to Sync Reporting Tags

      It would be nice to be able to sync reporting tags in Zoho Finance to a custom field in Zoho CRM. My use case is for a Customer in Finance to an Account in CRM (and vice-versa, of course), but I'm sure it's pretty obvious that this could also be used
    • Join the Zoho Desk Virtual Classroom Training (VCRT)

      Hello everyone, Have you heard about Zoho's Virtual Classroom Training (VCRT)? Zoho Desk's Virtual Classroom Training offers end-to-end training for Zoho Desk users. Join the VCRT and get hands-on guidance for setting up Zoho Desk and getting your business
    • Make Rich Text fields available in Canva Print Views

      Everything is on the title. I don't really understand why this is not already possible as Rich Text Fields are available in Canva Detailed Views for example.
    • Zoho CRM Approval Process based on Field Update

      Hello, In current structure, Zoho CRM send records to approval based on record creation and edit.  I think, it should be to set approval process trigger based on any field update in record. When the user update any field, the record can assign to approval
    • Approve records efficiently: Useful enhancements to My Jobs module and Approval process in Zoho CRM

      Dear Customers, As you might know, approval process is a process automation tool that allows you to automate approvals in your organization and My Jobs is where you approve requests from a single point of view. Here's how you'd go about it: You’d add
    • Filter isn't

      The ability to filter the history of a given flow to a specific status however it would be great to have the ability to filter to a status that isn't something for example if i want to find all history that isn't complete.
    • Introducing the Store Locator widget

      Hello everyone! Your website is often the first place customers visit before deciding where to shop. But when they can't quickly find the nearest store, check business hours, or get directions, many leave your website and search elsewhere. Every extra
    • Important updates to your connectors

      Hello everyone, Greeting from Zoho Creator! We're excited to announce that we'll be rolling out significant backend updates to Zoho Creator's built-in connectors to enhance security by following the latest frameworks. The existing version of some of the
    • Important updates to your Salesforce integrations in Zoho Creator

      Hello everyone, We're writing to inform you of an important change regarding Salesforce integrations in Zoho Creator. Salesforce has introduced new security requirements for third-party platforms that connect with their services via APIs. To comply with
    • Password Policy in Zoho Mail: Set password rules to keep your organization secure

      Weak or repetitive passwords are one of the most common causes of unauthorized account access in organizations. Zoho Mail's Password Policy feature allows administrators to define and enforce specific password requirements for all users in the organization,
    • What is Workqueue and how to hide it?

      Hi, My CRM suddenly have this "Workqueue", may I ask how to set the permission of this tab?
    • Zoho Community Digest - July 2026| Part 4

      Hi everyone, and welcome back! We're closing out July with a strong final week, from a major LinkedIn integration in Zoho Recruit to AI-powered forecasting in Zoho Analytics. There are also a few heads-ups worth noting, including API changes in Zoho CRM
    • Zoho CRM Community Digest - July 2026| Part 2

      Hello everyone! The second half of July brought five CRM updates, including a heads-up for developers on API changes coming in October, one Quick Win on keeping your attribution data intact through lead conversion, two Dev's Corner threads worth bookmarking,
    • Keeping project teams in the know with Zoho Cliq

      Project management is all about processes, data flow, and maintaining order. But communicating appropriate information at crucial times to stakeholders is as important as the moving parts of a project. Zoho Cliq can facilitate effective communication
    • Enable Credit Note creation for Sales Returns BEFORE receiving goods

      Currently, it is not possible to issue a Credit Note linked to a Sales Return until the goods have been officially marked as "received" in the system. In our business, we often need to issue a credit note to our clients immediately upon the initiation
    • Getting Internal Server Error message when filing for MTD

      I am trying to file for the MTD submission, and after I filled in all the information and click (Fetch Obligation) this message "Internal Server Error [500]" pops up. I have been trying for awhile and its still the same. What shall I do as today is deadline
    • No access to change view permission for team members

      Hi, I want team members to be able to update the percentage progress on their goals at mid year. Currently they cannot edit this, they can only update the comments against the goals. The ability to add view permission to goal progress for team members
    • Next Page