CVE-2026-50129: Mastodon: Persistent anonymous DoS via unhandled NoMethodError in MATH_TRANSFORMER
Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.11, 4.4.18, and 4.3.24, a DoS can be triggered by (Uncaught Exception vulerability), due to missing exception handling in the math sanitizer. Malformed <math> nodes can result in a DoS of a whole server or targeted users services, depending on the type of action that includes the malformed nodes and the services interacting with it. This vulnerability is fixed in 4.5.11, 4.4.18, and 4.3.24.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 4.5.11 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 4.4.18 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 4.3.24
Event History
Frequently Asked Questions
What is the severity of CVE-2026-50129?
The severity of CVE-2026-50129 is rated high with a score of 7.5.
What type of vulnerability is CVE-2026-50129?
CVE-2026-50129 is classified as a denial-of-service (DoS) vulnerability caused by unhandled exceptions in the math transformer.
How can CVE-2026-50129 impact a Mastodon server?
CVE-2026-50129 can lead to a denial-of-service condition that may affect the availability of the entire Mastodon server.
How do I fix CVE-2026-50129?
To fix CVE-2026-50129, update to Mastodon versions 4.5.11, 4.4.18, or 4.3.24 or later.
Which versions of Mastodon are affected by CVE-2026-50129?
Versions of Mastodon prior to 4.5.11, 4.4.18, and 4.3.24 are affected by CVE-2026-50129.