What is CVE-2021-37865?

CVE-2021-37865 is a medium-severity vulnerability in Mattermost, classified under Uncontrolled Resource Consumption. CVSS score: 4.3/10. Published 2022-01-18.

How severe is CVE-2021-37865?

Medium severity. CVSS v3 base score is 4.3 out of 10.

Resource exhaustion in Mattermost

CVE-2021-37865

Mattermost 6.2 and earlier fails to sufficiently process a specifically crafted GIF file when it is uploaded while drafting a post, which allows authenticated users to cause resource exhaustion while processing the file, resulting in server-side Denial of Service.

Vulnerability class: DoS (Denial of Service)

Published 2022-01-18 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L.

EPSS exploit prediction

EPSS: 0.009 (58.0th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 58th percentile — 58.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.009 · newest: 0.009 · change: 0.000

Affected products

Mattermost — versions unspecified, 6.1.1, 6.0.4

Weakness classification (CWE)

CWE-400 — Uncontrolled Resource Consumption

References

mattermost.com/security-updates/ (Vendor Advisory)
hackerone.com/reports/1428260 (Permissions Required)

Frequently asked questions

What is CVE-2021-37865?: CVE-2021-37865 is a medium-severity vulnerability in Mattermost, classified under Uncontrolled Resource Consumption. CVSS score: 4.3/10. Published 2022-01-18.
How severe is CVE-2021-37865?: Medium severity. CVSS v3 base score is 4.3 out of 10.