XSS in Mattermost

CVE-2021-37859

Fixed a bypass for a reflected cross-site scripting vulnerability affecting OAuth-enabled instances of Mattermost.

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.033 (87.2th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.1 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:L.

Affected products

Mattermost — versions 5.34.5, 5.35.4, 5.32.0

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

Public proof-of-concept exploits

References

responsibledisclosure@mattermost.com (x_refsource_MISC, Vendor Advisory)

Frequently asked questions

What is CVE-2021-37859?: CVE-2021-37859 is a high-severity vulnerability in Mattermost, classified under Cross-site Scripting. CVSS score: 7.1/10. Published 2021-08-05.
How severe is CVE-2021-37859?: High severity. CVSS v3 base score is 7.1 out of 10.
Is CVE-2021-37859 known to be exploited?: 3 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.