CVE-2026-97701Zulip: Missing content-length limit on POST /messages/render allows denial-of-service via oversized requests
- 6.5MediumCVSS base score
- 0.43%Exploitation in 30 daysEPSS · top 62% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By GitHub_M
- 41 days later
· 41 days later
Published
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | Medium6.5 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
| NVDNVD · Awaiting Analysis | 3.1 | Medium6.5 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.43% · top 62% of all CVEs (14 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.5.
Affected products
References
References6
- https://github.com/zulip/zulip/security/advisories/GHSA-m257-w4r5-5rmf (opens in a new tab)x_refsource_CONFIRM
- https://github.com/zulip/zulip/pull/39913 (opens in a new tab)x_refsource_MISC
- https://github.com/zulip/zulip/commit/31773c77c501391ede0fa8ec727f39508664e0ae (opens in a new tab)x_refsource_MISC
- https://github.com/zulip/zulip/commit/4d94dd2ee6337a4b3351694dd314a45d3fe11031 (opens in a new tab)x_refsource_MISC
- https://github.com/zulip/zulip/releases/tag/12.2 (opens in a new tab)x_refsource_MISC
- https://zulip.readthedocs.io/en/latest/overview/changelog.html#zulip-server-12-2 (opens in a new tab)x_refsource_MISC
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-117032 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-97701)Record last updated .