CVE-2026-97701
Zulip: Missing content-length limit on POST /messages/render allows denial-of-service via oversized requests
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.
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| zulip zulip |
< 12.2 (affected) | CNA: GitHub_M |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 3.1 / 6.5 medium |
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H | CNA: GitHub_M |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://github.com/zulip/zulip/security/advisories/GHSA-m257-w4r5-5rmfCNA: GitHub_M · x_refsource_CONFIRM
- https://github.com/zulip/zulip/pull/39913CNA: GitHub_M · x_refsource_MISC
- https://github.com/zulip/zulip/commit/31773c77c501391ede0fa8ec727f39508664e0aeCNA: GitHub_M · x_refsource_MISC
- https://github.com/zulip/zulip/commit/4d94dd2ee6337a4b3351694dd314a45d3fe11031CNA: GitHub_M · x_refsource_MISC
- https://github.com/zulip/zulip/releases/tag/12.2CNA: GitHub_M · x_refsource_MISC
- https://zulip.readthedocs.io/en/latest/overview/changelog.html#zulip-server-12-2CNA: GitHub_M · x_refsource_MISC
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