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.

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History

Wed, 04 Nov 2026 19:15:00 +0000

Type Values Removed Values Added
Description 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.
Title Zulip: Missing content-length limit on POST /messages/render allows denial-of-service via oversized requests
Weaknesses CWE-770
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-11-04T20:31:41.109Z

Reserved: 2026-09-24T21:43:37.209Z

Link: CVE-2026-97701

cve-icon Vulnrichment

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cve-icon NVD

Status : Received

Published: 2026-11-04T19:17:41.793

Modified: 2026-11-04T19:17:41.793

Link: CVE-2026-97701

cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses