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CVE-2026-3109Missing timestamp validation in Zoom webhook handler
- 2.2LowCVSS base score
- 0.31%Exploitation in 30 daysEPSS · top 76% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
Mattermost Plugins versions <=11.4 10.11.11.0 fail to validate webhook request timestamps which allows an attacker to corrupt Zoom meeting state in Mattermost via replayed webhook requests. Mattermost Advisory ID: MMSA-2026-00584
Timeline
ID reserved
By Mattermost
- 30 days later
· 30 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 |
|---|---|---|---|
| MattermostCNA (assigner) | 3.1 | Low2.2 | CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L |
| NVDNVD · Analyzed | 3.1 | Low2.2 | CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L |
- EPSS (exploitation in 30 days)
- 0.31% · top 76% of all CVEs (14 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
Loading the EPSS history…
The list uses the assigner's score when there is one, then CISA's, then NVD's: Low 2.2.
Affected products
- affected ≤ 10.11.11
- unaffected 11.5.0
- unaffected 10.11.12
What to do
Solution: Update Mattermost Plugins to versions 11.5.0, 10.11.12 or higher.
References
References1
- MMSA-2026-00584 (opens in a new tab)vendor-advisory
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-2026-16236 (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-2026-3109)Record last updated .