CVE-2026-6961

CVE-2026-6961: Path traversal via unsanitized FileInfo.Name in Mattermost federation sync

HIGH

7.6

CVSS Score

Published: June 12, 2026 at 03:56 PM UTC

Updated: June 18, 2026 at 03:45 PM UTC

2 products affected across 1 vendorMattermost ServerMattermost

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Severity

HIGH7.6

Exploit prediction

EPSS 0.3%

SSVC

No known exploit

Description

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

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Mattermost Server · Mattermost

95%

10.11.0 ≤ v < 10.11.1711.5.0 ≤ v < 11.5.511.6.0 ≤ v < 11.6.2

Affected range stops below 10.11.17, so it looks safe — our inference, not a vendor statement

Affected range stops below 11.5.5, so it looks safe — our inference, not a vendor statement

Affected range stops below 11.6.2, so it looks safe — our inference, not a vendor statement

Mattermost · Mattermost

60%

10.11.0 ≤ v ≤ 10.11.1510.11.0 ≤ v ≤ 10.11.1611.5.0 ≤ v ≤ 11.5.411.6.0 ≤ v ≤ 11.6.110.11.0 11.5.0 11.6.0

Vendor states this is fixed in 10.11.16 (unaffected)

Vendor states this is fixed in 10.11.17 (unaffected)

Vendor states this is fixed in 11.5.5 (unaffected)

Vendor states this is fixed in 11.6.2 (unaffected)

Vendor states this is fixed in 11.7.0 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://mattermost.com/security-updates

References (1)

Vendor Advisory

Source: cverecord

https://mattermost.com/security-updates

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.6HIGHMattermost

Attack Vector: NETWORK
Complexity: LOW
Privileges: HIGH
User Interaction: NONE
Scope: CHANGED
Confidentiality: NONE
Integrity: HIGH
Availability: LOW

Vector?

Quick Info

StatusANALYZED

CWE

CWE-22

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