Users can view the contents of an archived channel when access is explicitly denied by the system admin

published 2022-01-18 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-24342

cvss: 2.6; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.6%; EPSS 0.6% chance of exploitation in 30 days, percentile 48%
public exploits: 0; none known

Mattermost 6.1 and earlier fails to sufficiently validate permissions while viewing archived channels, which allows authenticated users to view contents of archived channels even when this is denied by system administrators by directly accessing the APIs.

Patch / fix

fixed in 1

Mattermost Mattermost 6.2

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 23 mo ago (2024-12-06)

Exploit prediction

0.58% chance of exploitation in the next 30 days, higher than 48% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	2.6	CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N
NVD	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
NVD	2.0	4.0	AV:N/AC:L/Au:S/C:P/I:N/A:N

Affected products

Mattermost Mattermost

Classification

Weakness

CWE-284 Improper Access Control
CWE-863 Incorrect Authorization

References

mattermost.com /security-updates/
vendor-advisory

Sources

CVE List CVE-2021-37864
NVD CVE-2021-37864

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