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CVE-2026-50128

Mastodon: Spoofing of attribution domains

Published: Jun 24, 2026Updated: Jun 25, 2026 Sources: CVE List NVDCWE-354
5.3MEDIUM
NVD MITRE
EPSS Score
0.2%
Top 92.1%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
No Fix Available
Self-Check
Not available

Description

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.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:LA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:LIntegrity
Low
A:NAvailability
None
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Weaknesses

CWE-354

Affected Products

mastodon
oss-projectaka mastodon/mastodon
mastodonOn-prem
Communications / messaging-chat

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

References

https://github.com/mastodon/mastodon/security/advisories/GHSA-rwcw-vq68-g34p
github.com
https://github.com/gogs/gogs/security/advisories/GHSA-pwx3-qcgw-vh7h
github.com

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