CVE-2021-37863

Name: CVE-2021-37863
Creator: NVD / NIST
Published: 2021-12-17T17:15:12.987+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.7/10EPSS 0.83%

Last modified Jun 17, 2026

CVE-2021-37863 is a medium-severity vulnerability rated 5.7/10 on the CVSS scale. Mattermost 6.0 and earlier fails to sufficiently validate parameters during post creation, which allows authenticated attackers to cause a client-side crash of the web application via a maliciously crafted post.. EPSS estimates a 0.83% chance of exploitation in the next 30 days.

Description

Mattermost 6.0 and earlier fails to sufficiently validate parameters during post creation, which allows authenticated attackers to cause a client-side crash of the web application via a maliciously crafted post.

Metrics

CVSS 3.1

5.7/10

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

EPSS Probability

0.83%

53.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Mattermost	Mattermost Server	<= 6.0

References

https://hackerone.com/reports/1253732Permissions Required
https://mattermost.com/security-updates/Vendor Advisory
https://hackerone.com/reports/1253732Permissions Required
https://mattermost.com/security-updates/Vendor Advisory

Timeline

Published: Dec 17, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-37863?

How severe is CVE-2021-37863?

CVE-2021-37863 has a CVSS score of 5.7/10 (MEDIUM severity). The EPSS model estimates a 0.83% probability of exploitation in the next 30 days.

How do I fix CVE-2021-37863?

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-2021-37863?

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

Scan your code now

Source: NVD / NIST