Is CVE-2026-50129 in the CISA KEV catalog?

No. CVE-2026-50129 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-50129?

CVE-2026-50129 has a CVSS v3 base score of 7.5 (HIGH).

What is the EPSS score for CVE-2026-50129?

CVE-2026-50129 has an EPSS score of 0.26% (18th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2026-50129

HIGH

7.5

CVSS v3

NVD

Description

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.

CWE-248

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

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

Exploit Intelligence

0.26%probability of exploitation in 30 days

18thpercentile

Low risk: more likely to be exploited than 18% of all known CVEs.

References

https://github.com/mastodon/mastodon/security/advisories/GHSA-qrgq-9fx2-vf2r

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-25.