CVE-2026-97701

Zulip: Missing content-length limit on POST /messages/render allows denial-of-service via oversized requests

Published Nov 4, 2026 CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Zulip
Zulip zulip
Vendors & Products Zulip
Zulip zulip
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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Nov 4, 2026, 8:31 PM
Reserved
Sep 24, 2026, 9:43 PM
Status
Awaiting Analysis
Published
Nov 4, 2026, 7:17 PM
Modified
Nov 6, 2026, 9:29 PM