Mastodon up to 4.4.17/4.5.10 attributionDomains integrity check

Summaryinfo

A vulnerability has been found in Mastodon up to 4.4.17/4.5.10 and classified as problematic. Impacted is an unknown function. The manipulation of the argument attributionDomains leads to integrity check. This vulnerability is referenced as CVE-2026-50128. Remote exploitation of the attack is possible. No exploit is available. The affected component should be upgraded.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Mastodon up to 4.4.17/4.5.10. This issue affects an unknown part. The manipulation of the argument attributionDomains with an unknown input leads to a integrity check vulnerability. Using CWE to declare the problem leads to CWE-354. The product does not validate or incorrectly validates the integrity check values or "checksums" of a message. This may prevent it from detecting if the data has been modified or corrupted in transmission. Impacted is integrity. The summary by CVE is:

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.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-50128 since 06/03/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are known, but no exploit is available.

Upgrading to version 4.4.18 or 4.5.11 eliminates this vulnerability.

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Name

• Mastodon

Version

• 4.4.0
• 4.4.1
• 4.4.2
• 4.4.3
• 4.4.4
• 4.4.5
• 4.4.6
• 4.4.7
• 4.4.8
• 4.4.9
• 4.4.10
• 4.4.11
• 4.4.12
• 4.4.13
• 4.4.14
• 4.4.15
• 4.4.16
• 4.4.17
• 4.5.0
• 4.5.1
• 4.5.2
• 4.5.3
• 4.5.4
• 4.5.5
• 4.5.6
• 4.5.7
• 4.5.8
• 4.5.9
• 4.5.10

Website

• Product: https://github.com/mastodon/mastodon/

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