CVE-2021-37859

Name: CVE-2021-37859
Creator: NVD / NIST
Published: 2021-08-05T20:15:09.533+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.1/10EPSS 3.29%

Last modified Jun 17, 2026

CVE-2021-37859 is a medium-severity vulnerability rated 6.1/10 on the CVSS scale. Fixed a bypass for a reflected cross-site scripting vulnerability affecting OAuth-enabled instances of Mattermost.. EPSS estimates a 3.29% chance of exploitation in the next 30 days.

Description

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

Metrics

CVSS 3.1

6.1/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS Probability

3.29%

86.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Mattermost	Mattermost	>= 5.32.0, < 5.34.5
Mattermost	Mattermost	>= 5.35.0, < 5.35.4
Mattermost	Mattermost	>= 5.36.0, < 5.36.1

References

https://mattermost.com/security-updates/Vendor Advisory
https://mattermost.com/security-updates/Vendor Advisory

Timeline

Published: Aug 5, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-37859?

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

How severe is CVE-2021-37859?

CVE-2021-37859 has a CVSS score of 6.1/10 (MEDIUM severity). The EPSS model estimates a 3.29% probability of exploitation in the next 30 days.

How do I fix CVE-2021-37859?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-37859?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST