CVE-2026-97701 json
Zulip: Missing content-length limit on POST /messages/render allows denial-of-service via oversized requests
published 3mo ago modified 5d ago also EUVD-2026-117032 , GHSA-m257-w4r5-5rmf
Unreviewed: the maintainers' own advisory
Published by the maintainers on their GitHub repository zulip/zulip. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.
- cvss
- 6.5
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.4%
- EPSS 0.4% chance of exploitation in 30 days, percentile 37%
- public exploits
- 0
- none known
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 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.
Patch / fix
- zulip zulip 12.2
- zulip zulip_server 12.2
- github.com/zulip/zulip@31773c7 commit
- github.com/zulip/zulip@4d94dd2 commit
- github.com/zulip/zulip#39913 pull request
- github.com/zulip/zulip/releases/tag/12.2 release
Is CVE-2026-97701 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 7d ago
Exploit prediction
0.43% chance of exploitation in the next 30 days, higher than 37% of all scored CVEs (FIRST EPSS, 2026-11-11).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 6.5 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
Affected products
- zulip zulip
Classification
- Weakness
-
- CWE-770 Allocation of Resources Without Limits or Throttling
References
- github.com /zulip/zulip/pull/39913
- github.com /zulip/zulip/commit/31773c77c501391ede0fa8ec727f39508664e0ae
- github.com /zulip/zulip/commit/4d94dd2ee6337a4b3351694dd314a45d3fe11031
-
github.com
/zulip/zulip/security/advisories/GHSA-m257-w4r5-5rmf
advisory
- github.com /zulip/zulip/releases/tag/12.2
- zulip.readthedocs.io /en/latest/overview/changelog.html#zulip-server-12-2
Sources
- CVE List CVE-2026-97701
- NVD CVE-2026-97701
- Maintainer advisory GHSA-m257-w4r5-5rmf
Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
The maintainers of zulip/zulip published their own advisory on GitHub. Reviewed sources take precedence over it.
CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.