Path Traversal in Template Upload Allows Uploading Files Outside Target Directory

published 2025-08-21 14 mo ago modified 2026-06-17 4 mo ago also GHSA-x67c-v8jr-p29r , GO-2025-3907 , EUVD-2025-25412

cvss: 6.8; 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 35%
public exploits: 0; none known

Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.9.x <= 10.9.2 fails to sanitize path traversal sequences in template file destination paths, which allows a system admin to perform path traversal attacks via malicious path components, potentially enabling malicious file placement outside intended directories.

Patch / fix

fixed in 3

go github.com/mattermost/mattermost-server 9.11.18, 9.11.18+incompatible, 10.5.9, 10.5.9+incompatible, 10.8.4, 10.8.4+incompatible, 10.9.3, 10.9.3+incompatible
go github.com/mattermost/mattermost/server/v8 8.0.0-20250708065844-b38e2eccda18
Mattermost Mattermost 9.11.18, 10.5.9, 10.8.4, 10.9.3, 10.10.0

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 14 mo ago (2025-08-21)

Exploit prediction

0.41% chance of exploitation in the next 30 days, higher than 35% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	6.8	CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:N
NVD	3.1	4.9	CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N
GitHub	3.1	6.8	CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:N

Affected packages

ecosystem	package	affected	fixed in
go	github.com/mattermost/mattermost-server	>=10.8.0, <10.8.4 >=10.5.0, <10.5.9 >=9.11.0, <9.11.18 >=10.9.0, <10.9.3 >=9.11.0+incompatible, <9.11.18+incompatible >=10.5.0+incompatible, <10.5.9+incompatible >=10.8.0+incompatible, <10.8.4+incompatible >=10.9.0+incompatible, <10.9.3+incompatible	10.8.4 10.5.9 9.11.18 10.9.3 9.11.18+incompatible 10.5.9+incompatible 10.8.4+incompatible 10.9.3+incompatible
go	github.com/mattermost/mattermost/server/v8	<8.0.0-20250708065844-b38e2eccda18	8.0.0-20250708065844-b38e2eccda18
go	github.com/mattermost/mattermost-server/v5	<=5.39.5 all versions	no fix listed
go	github.com/mattermost/mattermost-server/v6	<=6.7.2 all versions	no fix listed

Affected products

Mattermost Mattermost

Classification

Weakness

CWE-22 Improper Limitation of a Pathname to a Restricted Directory

References

mattermost.com /security-updates
web, vendor-advisory
nvd.nist.gov /vuln/detail/CVE-2025-8023
advisory
github.com /mattermost/mattermost
package
pkg.go.dev /vuln/GO-2025-3907
web
github.com /advisories/GHSA-x67c-v8jr-p29r
advisory

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary