CSRF vulnerability in UpdateAccessControlPolicyActiveStatus endpoint

published 2026-03-25 7 mo ago modified 2026-06-25 4 mo ago also GHSA-rmhw-c3xr-m3xx , GO-2026-5629 , EUVD-2026-15806

cvss: 4.6; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.1%; EPSS 0.1% chance of exploitation in 30 days, percentile 2%
public exploits: 0; none known

Mattermost versions 11.2.x <= 11.2.2, 10.11.x <= 10.11.10, 11.4.x <= 11.4.0, 11.3.x <= 11.3.1 fail to properly validate CSRF tokens in the /api/v4/access_control_policies/{policy_id}/activate endpoint, which allows an attacker to trick an admin into changing access control policy active status via a crafted request.. Mattermost Advisory ID: MMSA-2026-00578

Patch / fix

fixed in 3 distros 1

go github.com/mattermost/mattermost/server/v8 10.11.11, 11.2.3, 11.3.2, 11.4.1
go github.com/mattermost/mattermost-server 10.11.11+incompatible, 11.2.3+incompatible, 11.3.2+incompatible, 11.4.1+incompatible
Mattermost Mattermost 10.11.11, 11.2.3, 11.3.2, 11.4.1, 11.5.0

govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1

opensuse advisories openSUSE-SU-2026:21483-1

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 7 mo ago (2026-03-25)

Exploit prediction

0.13% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	4.6	CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N
GitHub	3.1	4.6	CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N

Affected packages

ecosystem	package	affected	fixed in
go	github.com/mattermost/mattermost/server/v8	>=11.4.0-rc1, <11.4.1 >=11.3.0-rc1, <11.3.2 >=11.2.0-rc1, <11.2.3 >=10.11.0-rc1, <10.11.11 >=8.0.0-20260105080200-d27a2195068d, <10.11.11 >=8.0.0-20260105080200-d27a2195068d	11.4.1 11.3.2 11.2.3 10.11.11
go	github.com/mattermost/mattermost-server	>=10.11.0-rc1+incompatible, <10.11.11+incompatible >=11.2.0-rc1+incompatible, <11.2.3+incompatible >=11.3.0-rc1+incompatible, <11.3.2+incompatible >=11.4.0-rc1+incompatible, <11.4.1+incompatible	10.11.11+incompatible 11.2.3+incompatible 11.3.2+incompatible 11.4.1+incompatible
go	github.com/mattermost/mattermost-server/v5	all versions	no fix listed
go	github.com/mattermost/mattermost-server/v6	all versions	no fix listed

Affected products

Mattermost Mattermost

Classification

Weakness

CWE-352 Cross-Site Request Forgery

References

mattermost.com /security-updates
vendor-advisory, web
nvd.nist.gov /vuln/detail/CVE-2026-27659
advisory
github.com /mattermost/mattermost
package
github.com /advisories/GHSA-rmhw-c3xr-m3xx
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