What’s Vulnerable › Vulnerabilities

CVE-2023-5196: DoS via Channel Notification Properties

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2023-09-29 · updated 2026-06-17
• Weakness: CWE-400

Description

Mattermost fails to enforce character limits in all possible notification props allowing an attacker to send a really long value for a notification_prop resulting in the server consuming an abnormal quantity of computing resources and possibly becoming temporarily unavailable for its users.

Affected products

• Mattermost App Framework: from 7.0.0 before 7.8.10; from 8.0.0 before 8.0.2; from 8.1.0 before 8.1.1 — fixed in 7.8.10, 8.0.2, 8.1.1

How to fix

Upgrade to a fixed version: Mattermost App Framework 7.8.10, 8.0.2, 8.1.1. Check the vendor advisory for mitigations.

References

• https://mattermost.com/security-updates
• https://mattermost.com/security-updates

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