Unauthorized access on archived channels

published 2024-09-26 2 y ago modified 2026-06-17 4 mo ago also BIT-mattermost-2024-42406 , EUVD-2024-39606

cvss: 5.4; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 12%
public exploits: 0; none known

Mattermost versions 9.11.x <= 9.11.0, 9.10.x <= 9.10.1, 9.9.x <= 9.9.2 and 9.5.x <= 9.5.8 fail to properly authorize requests when viewing archived channels is disabled, which allows an attacker to retrieve post and file information about archived channels. Examples are flagged or unread posts as well as files.

Patch / fix

fixed in 2

bitnami mattermost 9.5.9, 9.9.3, 9.10.2
Mattermost Mattermost 9.5.9, 9.9.3, 9.10.2, 9.11.1, 10.0.0

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 2 y ago (2024-09-26)

Exploit prediction

0.22% chance of exploitation in the next 30 days, higher than 12% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	5.4	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
NVD	3.1	5.4	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
OSV	3.1	5.4	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

Affected packages

ecosystem	package	affected	fixed in
bitnami	mattermost	>=9.5.0, <9.5.9 >=9.9.0, <9.9.3 >=9.10.0, <9.10.2 >=9.11.0-rc1, <=9.11.0-rc1 >=9.11.0-rc2, <=9.11.0-rc2 >=9.11.0-rc3, <=9.11.0-rc3 >=9.11.0, <=9.11.0	9.5.9 9.9.3 9.10.2

Affected products

Mattermost Mattermost

Classification

Weakness

CWE-284 Improper Access Control

References

mattermost.com /security-updates
vendor-advisory, web
nvd.nist.gov /vuln/detail/CVE-2024-42406
web

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