What’s Vulnerable › Vulnerabilities

CVE-2021-37865: Server-side Denial of Service while processing a specifically crafted GIF file

• Severity: medium (CVSS 5.7 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.9% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2022-01-18 · updated 2026-06-17
• Weakness: CWE-400

Description

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.

Affected products

• Mattermost App Framework: through 6.2.0

References

• https://hackerone.com/reports/1428260
• https://mattermost.com/security-updates/
• https://hackerone.com/reports/1428260
• https://mattermost.com/security-updates/

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