CVE-2026-50128

mediumpriority · track · 0EPSS 0.002 · 8 %ileEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.18% (8th) EPSS

CVSS 5.3 · medium

Is it mine?

4 products

Check your exposure

Who says so?

3 sources

cnnvd · enisa_euvd · osv

EPSS · scored 2026-10-28

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

Technical severity, 0–10. One row per scoring source.

5.3

010

base score 0–10 · higher = more severe · hover a vector to decode

v3.15.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:Nsecondary · ENISA EU

v3.15.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:Nsecondary · security-advisories@github.comexploitability 3.9 · impact 1.4

v3.14.9mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N/E:Usecondary · CVSS-BT (t0sche)

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: none · Automatable: yes · Technical Impact: partialcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-354US

affected products (4)

Products and version ranges known to be affected.

mastodon mastodon4.3.0, → 4.4.18enisa_euvdEU
mastodon mastodon4.5.0-beta.1, → 4.5.11enisa_euvdEU
Bitnami mastodon4.3.0 → 4.4.18osvUSpkg:bitnami/mastodon
Bitnami mastodon4.5.0 → 4.5.11osvUSpkg:bitnami/mastodon

advisories (1)

Vendor and ecosystem advisories describing this.

BIT-mastodon-2026-50128Mastodon: Spoofing of attribution domains2026-07-06vendor · osvUS
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.

also known as (2)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd osv NVD CVE.org MITRE

published 2026-06-24modified 2026-06-25

references (5)

External citations — patches, advisories, analysis.

scry

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