CVE-2026-6340Memory Exhaustion via Malicious 7zip File Upload
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No exploitation reported and no EPSS estimate yet.
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Free account, 1 product
Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to validate 7zip archive structure before processing which allows an authenticated attacker to cause server memory exhaustion and denial of service via uploading a specially crafted 7zip file with excessive folder declarations.. Mattermost Advisory ID: MMSA-2026-00573
- CVSS
- 4.3 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
- Weakness (CWE)
- CWE-789
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Mattermost
- NVD analysis
- Analyzed
- Record last updated
- May 18, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Mattermost Mattermost mattermost:mattermost (from the name) | from 11.5.0 through 11.5.1; from 10.11.0 through 10.11.13; from 11.4.0 through 11.4.3; 11.6.0 not affected; 11.5.2 not affected; 10.11.14 not affected; 11.4.4 not affected | CNA record |
mattermost mattermost_server mattermost:mattermost_server | from 10.11.0 before 10.11.14; from 11.4.0 before 11.4.4; from 11.5.0 before 11.5.2 | NVD |
References
- https://mattermost.com/security-updatesvendor-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.