Permalink previews displayed for posts in archived channels even if users are disallowed to view archived channels

published 2023-11-27 2 y ago modified 2026-09-10 1 mo ago also GHSA-jjr7-372r-cx7x , EUVD-2023-2991

cvss: 4.3; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.5%; EPSS 0.5% chance of exploitation in 30 days, percentile 43%
public exploits: 0; none known

Mattermost fails to check whether the “Allow users to view archived channels” setting is enabled during permalink previews display, allowing members to view permalink previews of archived channels even if the “Allow users to view archived channels” setting is disabled.

Patch / fix

fixed in 3

go github.com/mattermost/mattermost/server/v8 8.1.4, 9.0.2, 9.1.1
go github.com/mattermost/mattermost-server/v6 7.8.13
Mattermost Mattermost 7.8.13, 8.1.4, 9.0.2, 9.1.1

Exploit prediction

0.51% chance of exploitation in the next 30 days, higher than 43% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	4.3	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
NVD	3.1	4.3	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
GitHub	3.1	4.3	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

Affected packages

ecosystem	package	affected	fixed in
go	github.com/mattermost/mattermost/server/v8	>=9.1.0, <9.1.1 >=9.0.0, <9.0.2 <8.1.4	9.1.1 9.0.2 8.1.4
go	github.com/mattermost/mattermost-server/v6	<7.8.13	7.8.13

Affected products

Mattermost Mattermost

Classification

Weakness

CWE-200 Exposure of Sensitive Information to an Unauthorized Actor

References

mattermost.com /security-updates
web, vendor-advisory
nvd.nist.gov /vuln/detail/CVE-2023-43754
advisory
github.com /mattermost/mattermost
package

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