CVE-2026-50128: medium-severity vulnerability in mastodon
Mastodon: Spoofing of attribution domains
Published · Updated
33Vexday Risk Score
No sign of exploitation. It has a public proof of concept.
ssvc Attendcvss 5.3epss 0.2%
exploitation probability
0.2%top 93% of all CVEs
observed exploitation
nono source reports it
1 public exploit(s)
Mastodon is a free, open-source social network server based on ActivityPub. From 4.3.0 until 4.5.11 and 4.4.18, Mastodon has a feature to let websites credit authors of their articles. To prevent false attribution claims, Mastodon uses the attributionDomains JSON-LD term, however, an error in how it is defined makes Linked Data Signatures on the toot:attributionDomains property ineffective. An attacker can arbitrarily modify the attributionDomains value of a legitimately signed Update activity and bypass Mastodon’s signature verification. This vulnerability is fixed in 4.5.11 and 4.4.18.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Affected products
mastodon · mastodonpublic PoCs found — 1
cve_referencegithub.com/gogs/gogs/security/advisories/GHSA-pwx3-qcgw-vh7hunverified⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.
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