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

    • Marketing Tip #9: Track your traffic sources

      Not all marketing channels work equally well. Knowing whether your visitors come from Google, Instagram, or email helps you focus on what actually drives sales. Try this today: Check your Zoho Commerce reports or connect Zoho PageSense to see your top
    • Google Analytics import data inaccurate (as of October 11, 2025)

      We have Zoho Analytics connected to GA4 to import daily event data. This has been running without issue for a couple of years. However, a month ago we started noticing discrepancies. All data until October 10 lines up perfectly - October 11 onward is
    • Zoho Books | Product updates | November 2025

      Hello users, We’ve rolled out new features and enhancements in Zoho Books. From translating email notification templates to the new transaction locking restrictions, explore the updates designed to enhance your bookkeeping experience. Making Tax Digital
    • Insert Image into Notebook page

      Prior to today, I could add images to my notebook pages. Today when I tried to do this I got an error message that said something like, "There's been a problem on our end. Try again later." So, I've tried all the ways I know how, but I can't insert an
    • 【開催報告】名古屋 ユーザー交流会 Vol.2 2025/11/21 Zoho Analytics / Inventory で実現する在庫の"未来予測"

      ユーザーの皆さま、こんにちは。コミュニティチームの中野です。 11/21(金)に名古屋 ユーザー交流会 を開催しました。 本投稿では、当日実施したセッションの様子及び投影資料をお届けします。 会場にて参加できなかった皆さまも、ぜひご参照ください。 (Zoho 社員セッションの登壇資料については、11/28(金)開催の東京回の開催報告で共有いたします) 今年2回目の開催となる名古屋 ユーザー交流会では、株式会社エンツナクリエイト 野末さんによる Zoho Analytics / Inventory
    • Is there a way to automatically add Secondary Contacts (CCs) when creating a new ticket for specific customers?

      Some of our customers want multiple contacts to receive all notifications from our support team. Is there a way to automatically add secondary contacts to a ticket when our support team opens a new ticket and associates it with an account? This would
    • Improved RingCentral Integration

      We’d like to request an enhancement to the current RingCentral integration with Zoho. RingCentral now automatically generates call transcripts and AI-based call summaries (AI Notes) for each call, which are extremely helpful for support and sales teams.
    • Edit Pinned Comments in Zoho Desk

      It's great that private comments can now be pinned to the top of the ticket but what would be extremely helpful would be to allow for the pinned comment to be edited vs. having to find the comment in the ticket to edit it.
    • Updating Secondary Contact (CCs)

      We use Zoho Forms to capture the user request and integrated with Zoho Desk to raise tickets. Active Microsoft login is captured in our Zoho forms and registered as Primary contact in Zoho desk ticket. We also an have an option to raise ticket on behalf
    • blank page after login

      blank page after logging into my email account Thanks you
    • WriterTh

      After every space Writer goes to capital letters mode in my Android tablet. The cap mode stays till the second letter is typed in the word then it comes to normal mode.
    • Zoho writer unable to merge documents to PDF with basic fonts in Hebrew or fonts from my computer

      I created several forms that will be merged into PDF files through Zoho Writer and I am unable to receive the PDF in the basic fonts of the Hebrew language or in the fonts I have on my computer. The writer exports to PDF an exchange font that looks very
    • I have already created some Bots, Commands, and Widgets in Cliq, but I am still not seeing the “Create Extension” option in my account. Could you please help me enable or access this option?

    • Infinite loop of account verification

      Hi I can't do anything on my zoho account.  I always get this message Hi Sheriffo Ceesay As a security measure, you need to link your phone number with this account and verify it to proceed further. When ever I supply the details, it displays that the number is associated with another account. I don't have any other account on zoho so this is really annoying. 
    • How we cut CRM updates from ~20 minutes down to 2, our real workflow

      Updating the Zoho CRM after every call used to be one of the biggest time sucks for our team. By the time you write your notes, clean them up, fill in the fields, and log everything properly… you’ve easily lost 15–20 minutes per call. We started experimenting
    • Arattai App Features Update

      1. Offline Messaging & Sync Enable users to compose messages without internet and deliver them automatically via peer-to-peer methods (Bluetooth/WiFi Direct) when nearby users are available. This would be a game-changer for rural India with unreliable
    • How to add Product Add-Ons, Mandatory Forms, and Auto-Save Address in Zoho Commerce

      Hi all, I need help setting up several behaviors in Zoho Commerce. I can’t find the correct configuration options, so I want to confirm whether these are supported or if there is a workaround. 1. Product-Specific Add-Ons (Example: GWB Subscription) When
    • Zohomail

      Im trying to setup email address zoho
    • PROBLEMA

      Salve, non riesco a inviare email, e mi esce una tabela errore temporaneo. come posso risolvere il problema ?
    • Forever FREE Business Email with Zoho Mail

      Forever FREE Business Email with Zoho Mail: is it available?
    • Weekly Tips : Make collaboration effortless with Whiteboard in Zoho Mail

      Working with your team often means switching between emails, notes, and other applications just to explain an idea. Maybe you are trying to sketch a layout, plan a workflow, or quickly brainstorm ideas—with text alone, things can get confusing. So how
    • Formula field number of days between 2 dates

      Hi, I want to have a formula field which calculates the following: IF EndDate < TODAY and Oproep is true (this is a checkbox field) than EndDate - StartDate, otherwise TODAY - StartDate It should calculate the number of days How can I write this for
    • 'email address already exists'

      I deleted a user from my organization and want to use the same email address that user had, but the email address seems to still exist somewhere as I get 'email address already exists' when I try and create it. I have deleted the entire organization and
    • ZOHO reporting DKIM entries are not configured, when they have been configured and verified by 3rd parties

      Why is ZOHO reporting to my organisation users the following: "The DKIM entries in your domain's DNS records are not configured. Please contact your administrator for configuring DKIM to ensure optimal RSVP invite delivery." When I have configured the
    • Manage Bookings directly from Zoho Mail

      Greetings from the Zoho Bookings team! We’re introducing the new Zoho Bookings extension for Zoho Mail, designed to help you view appointments, copy time slots and share booking links without leaving your inbox. This integration brings scheduling right
    • My notes from the past 2 months have disappeared

      Hola, necesito ayuda urgente. Hoy, al iniciar sesión en mi Zoho Notebook como todos los días, me llevé una gran sorpresa al descubrir que todas mis notas de los últimos dos meses habían desaparecido. Estas notas son muy importantes para mí, ya que uso
    • How can I load a network into the cliq desktop app?

      I have both the standard cliq log in for my org and I am part of a cliq network. In the browser I can choose which I log in to. However, in teh desktop app if I log in it will alwasy load my org's cliq. Can I switch this to the network I have create
    • Ability to modify what displays in calendar invite?

      I am a long time calendly user and want to make the switch to bookings.  I understand that there is not currently a meets/hangouts integration, is one on the roadmap? Is there anyway I can modify the calendar invite to include the meet link?  I can add it to the emails no problem, but I would also like it to display on their calendar.  Is there some work around I can do to get it on the calendar?  Also am I able to modify the calendar event title?
    • Issue with Booking Confirmation Page Not Displaying, Leading to Customer Anxiety and Unnecessary Support Calls

      I am writing to express my growing concern regarding the confirmation process in Zoho Bookings, particularly the inconsistent display of the confirmation page after a successful payment. As a mobile service provider, I rely on Zoho Bookings platform for
    • Is it possible to turn off all capabilities for a customer to schedule, reschedule or cancel an appointment?

      Is it possible to turn off all capabilities for a customer to schedule, reschedule or cancel an appointment? I would like to set it up so only staff can schedule appointments. Is this possible?
    • Is there a way to generate a virtual meeting for a group service in Zoho Bookings?

      Are virtual meetings not supported for group services/meetings? I have integrated Zoom with one-on-one services, but I need a way to create an online group meeting. Thanks
    • Where we can change the icon in social preview

      Hi, we changed our logo, and the image that appear in preview (ex : when we post a appointment link somewhere) is still our old logo. I did change our logo in the org setting. https://bookings.zoho.com/app/#/home/dashboard/settings/basic-info?clview=false
    • Zoho Bookings changes Lead Source

      Hi. i would like to know if there's a way for Zoho Bookings to not change the lead source when booking a lead for an appointment as the lead source will be used in a report. Scenario: Lead source: Website after booking an appointment Lead source: Zoho Bookings Thanks. Dan
    • Need to set workflow or journey wait time (time delay) in minutes, not hours

      Minimum wait time for both Campaigns workflows and Marketing Automation journeys is one hour. I need one or the other to be set to several minutes (fraction of the hour). I tried to solve this by entering a fraction but the wait time data type is an integer
    • Suggestion: Associating Assets with Company in Zoho FSM

      Hello Team, I would like to share an idea based on practical experience. Currently, all assets in the Zoho FSM Asset module are linked to a specific contact person. I would like to know if it is possible to associate assets with a company instead. This
    • Zoho Inventory / Finance Suite - Extend Visibility of File Names on Attachment Fields

      Hi Inventory / Finance Suite team, I noticed recently that when you add an attachment field to a module in Inventory, only the first 8 characters of the file name are visible on the details view. 8 characters is not a useful amount and there is plenty
    • Many Notes Becoming Unusable

      Hello. The Notebook app is becoming unusable. I'm getting odd-looking results from my searches. Some of the notes, after clicking on them, show an update button that does absolutely nothing. Not sure what has happened, but it would be nice to get this
    • Kaizen #218: Actions APIs - Field Updates

      Hello all!! Welcome back to a fresh Kaizen week. In the previous weeks, we covered Workflow Rules APIs, Actions APIs - Email Notification APIs, and Tasks Update APIs. This week, we will continue with another Actions API - the Field Update API in Zoho
    • How Contract Types and Templates Form the Backbone of Zoho Contracts

      Every contract in Zoho Contracts starts with two essential elements: Contract Type and Template. These are not just administrative steps. They define how every contract in your organization is created, governed, and managed over time. Let us look at the
    • CRM Related list table in Zoho analytics

      In Zoho Analytics, where can I view the tables created from zoho crm related lists? For example, in my Zoho CRM setup, I have added the Product module as a related list in the Lead module, and also the Lead module as a related list in the Product module.
    • Next Page