---
id: CVE-2026-97701
title: >-
  Zulip: Missing content-length limit on POST /messages/render allows
  denial-of-service via oversized requests
summary: >-
  Zulip is an open-source team collaboration tool. In Zulip Server versions
  through 12.1, the authenticated POST /messages/render endpoint renders the
  content parameter without enforcing the normal message length limit used by
  message send…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-770
vendor: zulip
product: zulip
affected:
  - zulip < 12.2
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-04T20:31:27.892369Z'
published: '2026-11-04'
updated: '2026-11-04'
sourceUpdated: '2026-11-04T20:31:41.109Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-97701'
references:
  - url: 'https://github.com/zulip/zulip/security/advisories/GHSA-m257-w4r5-5rmf'
    label: 'https://github.com/zulip/zulip/security/advisories/GHSA-m257-w4r5-5rmf'
  - url: 'https://github.com/zulip/zulip/pull/39913'
    label: 'https://github.com/zulip/zulip/pull/39913'
  - url: >-
      https://github.com/zulip/zulip/commit/31773c77c501391ede0fa8ec727f39508664e0ae
    label: >-
      https://github.com/zulip/zulip/commit/31773c77c501391ede0fa8ec727f39508664e0ae
  - url: >-
      https://github.com/zulip/zulip/commit/4d94dd2ee6337a4b3351694dd314a45d3fe11031
    label: >-
      https://github.com/zulip/zulip/commit/4d94dd2ee6337a4b3351694dd314a45d3fe11031
  - url: 'https://github.com/zulip/zulip/releases/tag/12.2'
    label: 'https://github.com/zulip/zulip/releases/tag/12.2'
  - url: >-
      https://zulip.readthedocs.io/en/latest/overview/changelog.html#zulip-server-12-2
    label: >-
      https://zulip.readthedocs.io/en/latest/overview/changelog.html#zulip-server-12-2
tags:
  - cve.org
ingestedAt: '2026-11-05T21:36:00.562Z'
epss: 0.00433
epssPercentile: 0.37792
---

## Overview

Zulip is an open-source team collaboration tool. In Zulip Server versions through 12.1, the authenticated POST /messages/render endpoint renders the content parameter without enforcing the normal message length limit used by message send and edit operations. An authenticated user can submit Markdown up to the server body-size limit, causing disproportionate backend CPU consumption, and repeated or concurrent requests can degrade Markdown rendering performance or backend availability for other users. This issue is fixed in version 12.2.

## Affected

- `zulip < 12.2`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.