What is CVE-2023-1421?

CVE-2023-1421 is a low-severity vulnerability in Mattermost, classified under Cross-site Scripting. CVSS score: 3.5/10. Published 2023-03-15.

How severe is CVE-2023-1421?

Low severity. CVSS v3 base score is 3.5 out of 10.

XSS in Mattermost

CVE-2023-1421

A reflected cross-site scripting vulnerability in the OAuth flow completion endpoints in Mattermost allows an attacker to send AJAX requests on behalf of the victim via sharing a crafted link with a malicious state parameter.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2023-03-15 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 3.5 (Low). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 0.004 (33.1th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 33rd percentile — 33.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000

Affected products

Mattermost — versions 5.32.0, 7.7
Mattermost Server

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

mattermost.com/security-updates/ (Vendor Advisory)

Frequently asked questions

What is CVE-2023-1421?: CVE-2023-1421 is a low-severity vulnerability in Mattermost, classified under Cross-site Scripting. CVSS score: 3.5/10. Published 2023-03-15.
How severe is CVE-2023-1421?: Low severity. CVSS v3 base score is 3.5 out of 10.