Vulnerability

CVE-2026-6961

High· 7.6CVSS7.6

.rules3/5

Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 Mattermost fails to sanitize FileInfo.Name received from federated peers during shared channel file sync, which allows an attacker who controls a federated server to write files to arbitrary locations within the target server's filestore via path traversal sequences in the filename field.. Mattermost Advisory ID: MMSA-2026-00661

Threat signal

76/100

High

Severity

high

CVSS

7.6

EPSS

—

Active

CVSS

v3.1via NVDOpen in FIRST calculator →

7.6/ 10HIGHCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:H/A:L

Attack VectorNetworkExploitable remotely over the internet — no local access needed.
Attack ComplexityLowNo special conditions — exploit works reliably.
Privileges RequiredHighAdmin / root privileges required.
User InteractionNoneFully automated — no victim action needed.
ScopeChangedImpact extends beyond the vulnerable component (e.g. sandbox escape).
Confidentiality ImpactNoneNo confidentiality impact.
Integrity ImpactHighTotal compromise of integrity — full data modification possible.
Availability ImpactLowReduced performance / interruptions.

EPSS

No EPSS data

FIRST.org publishes EPSS daily. Coverage isn't universal — pre-disclosure CVEs and reserved IDs don't carry an EPSS score until at least one exploitation signal lands. Score will appear within 24 hours of the next EPSS pull.

Vendor VEX

No VEX statements published for CVE-2026-6961. Vendors publish VEX (Vulnerability Exploitability eXchange) to assert per-product whether a CVE is actually exploitable in their distribution.

SSVCTrack

Total impact on non-trivial mission systems

exploitation: none
automatable: no
impact: total
mission: support

Lifecycle

2026-06-12Published
2026-06-12Last modified1 source

References

https://mattermost.com/security-updates

No source-event history recorded yet. New revisions will appear here as ingestors re-fetch this CVE.