Vulnerability · CVE-2026-3109
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 repl…
Published Mar 26, 2026 · catalog updated Jun 17, 2026 · mattermost server
Check if you run it
No confirmed exploitation is on record for CVE-2026-3109. EPSS is 0.31%. Act only if a listed version of mattermost server is installed.
Gaps on this record
- No vendor fix or required action is stored. Compare the linked advisory before you change production.
- Severity
- Low2.2
- Known exploitation
- Not in CISA/VulnCheck KEV
- EPSS
- 0.31%
- Remediation
- Version ranges on file
- Affected products
- cpe mattermost/mattermost server · stated mattermost server
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
Are you affected?
Enter the version you run. The result uses only the ranges stored on this record.
The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.
- cpe mattermost/mattermost serverversion unspecified
- stated mattermost server<= 11.4
How to fix CVE-2026-3109
Recommended remediation
Affected version ranges suggest a fixed boundary. Verify against the vendor advisory for your release.
Official advisories
What to do
Three questions, each answered from this record only. Confirm the vendor advisory before you patch.
Should you patch?
No confirmed exploitation is on record for CVE-2026-3109. EPSS is 0.31%. Act only if a listed version of mattermost server is installed.
Which versions are affected?
Compare what you have installed with mattermost server <= 11.4. Compare the installed version with the linked vendor advisory before you change production.
What should an analyst verify?
CWE-754. EPSS 0.31%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.
Code
The project this record applies to. Exploit listings stay in References.
No public source repository is identified for this product.
Timeline
Detection, updates, and resolution for this record.
Mar 26, 2026 · NIST NVD
Detected
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
Jun 17, 2026 · NIST NVD
Updated
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
Sources
- CVE.orgVulnerability recordCVE-2026-3109
Official CVE identifier
cve.org - FIRST EPSSExploitation probabilityCVE-2026-3109
30-day exploitation probability 0.3%
first.org - NIST NVDVulnerability recordCVE-2026-3109
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
nvd.nist.gov
References
Freshness
Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.