CVE-2026-16251: Mattermost · Unthrottled Resource Allocation
Affects MattermostSource GCVE Database
Not known to be exploited · CVSS 6.5 Medium.
Data as of 29 Oct 2026, 22:01 UTC
Thin evidence
One scorer or none| CNA (Mattermost) | CVSS 3.1 | 6.5 |
|---|
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 16 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Mattermost Mattermost | Affected
| Fixed in– |
AI-suggested
Until a fix is available, consider limiting exposure of the image proxy feature or applying resource usage limits at the infrastructure level to mitigate potential memory exhaustion.
Description
CVE-2026-16251 is a vulnerability in Mattermost versions 11.7.0, 11.8.0, 11.9.0, and 11.10.0 where the application fails to limit the size of remote image responses buffered in memory during local image proxy direct fetches. This flaw allows a remote attacker to cause memory exhaustion on the server by sending a crafted oversized image response.