CVE-2026-10819 json
Mattermost Server Denial of Service via Animated GIF Emoji Upload
published 3mo ago modified 3mo ago also EUVD-2026-49254
- 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 36%
- public exploits
- 0
- none known
Summary
Mattermost versions 11.6.x <= 11.6.5, 10.11.x <= 10.11.20, 11.8.x <= 11.8.1, 11.7.x <= 11.7.4 fail to limit the number of frames and enforce the file size cap on animated GIF uploads, which allows an authenticated attacker to cause a denial of service via a crafted animated GIF uploaded as a custom emoji.. Mattermost Advisory ID: MMSA-2026-00695
Patch / fix
- Mattermost Mattermost 10.11.21, 11.6.6, 11.7.5, 11.8.2, 11.9.0
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Check with FencerCISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 3mo ago
Exploit prediction
0.42% chance of exploitation in the next 30 days, higher than 36% of all scored CVEs (FIRST EPSS, 2026-11-09).
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
- Mattermost Mattermost
Classification
- Weakness
-
- CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)
References
-
mattermost.com
/security-updates
vendor-advisory
Sources
- CVE List CVE-2026-10819
- NVD CVE-2026-10819
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