HTML injection via channel autocomplete

published 2023-11-27 2 y ago modified 2026-09-10 1 mo ago also GHSA-jcgv-3pfq-j4hr , EUVD-2023-2986

cvss: 3.1; 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 30%
public exploits: 0; none known

Mattermost fails to use innerText / textContent when setting the channel name in the webapp during autocomplete, allowing an attacker to inject HTML to a victim's page by create a channel name that is valid HTML. No XSS is possible though.

Patch / fix

fixed in 3

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

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 2 y ago (2023-12-04)

Exploit prediction

0.37% chance of exploitation in the next 30 days, higher than 30% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

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

Affected packages

ecosystem	package	affected	fixed in
go	github.com/mattermost/mattermost/server/v8	<8.1.4	8.1.4
go	github.com/mattermost/mattermost-server/v6	<7.8.13	7.8.13

Affected products

Mattermost Mattermost

Classification

Weakness

CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component

References

mattermost.com /security-updates
web, vendor-advisory
nvd.nist.gov /vuln/detail/CVE-2023-35075
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