CVE-2026-22246

mediumpriority · track · 17EPSS 0.003 · 19 %ileEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.27% (19th) EPSS

CVSS 4.3 · medium

Is it mine?

9 products

Check your exposure

Who says so?

4 sources

cnnvd · enisa_euvd · osv · nvd

EPSS · scored 2026-10-27

Mastodon is a free, open-source social network server based on ActivityPub. Mastodon 4.3 added notifications of severed relationships, allowing end-users to inspect the relationships they lost as the result of a moderation action. The code allowing users to download lists of severed relationships for a particular event fails to check the owner of the list before returning the lost relationships. Any registered local user can access the list of lost followers and followed users caused by any severance event, and go through all severance events this way. The leaked information does not include the name of the account which has lost follows and followers. This has been fixed in Mastodon v4.3.17, v4.4.11 and v4.5.4.

cvss

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

6.5

010

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

v3.14.3mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:Nprimary · NVD / NIST USexploitability 2.8 · impact 1.4

v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:Nsecondary · ENISA EU

v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:Nsecondary · security-advisories@github.comexploitability 2.8 · impact 3.6

v3.14mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N/E:Usecondary · CVSS-BT (t0sche)

ssvc

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

Trackcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-201US

affected products (9)

Products and version ranges known to be affected.

mastodon mastodon≤ < 4.3.17enisa_euvdEU
mastodon mastodon4.4.0-beta.1, → 4.4.11enisa_euvdEU
mastodon mastodon4.5.0-beta.1, → 4.5.4enisa_euvdEU
joinmastodon mastodon< 4.3.17nvdUScpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*
joinmastodon mastodon4.4.0 → 4.4.11nvdUScpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*
joinmastodon mastodon4.5.0 → 4.5.4nvdUScpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*
Bitnami mastodon< 4.3.17osvUSpkg:bitnami/mastodon
Bitnami mastodon4.4.0 → 4.4.11osvUSpkg:bitnami/mastodon
Bitnami mastodon4.5.0 → 4.5.4osvUSpkg:bitnami/mastodon

advisories (1)

Vendor and ecosystem advisories describing this.

BIT-mastodon-2026-22246Local Mastodon users can enumerate and access severed relationships of every other local user2026-01-13vendor · osvUS
Mastodon is a free, open-source social network server based on ActivityPub. Mastodon 4.3 added notifications of severed relationships, allowing end-users to inspect the relationships they lost as the result of a moderation action. The code allowing users to download lists of severed relationships for a particular event fails to check the owner of the list before returning the lost relationships. Any registered local user can access the list of lost followers and followed users caused by any severance event, and go through all severance events this way. The leaked information does not include the name of the account which has lost follows and followers. This has been fixed in Mastodon v4.3.17, v4.4.11 and v4.5.4.

also known as (3)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd osv nvd NVD CVE.org MITRE

published 2026-01-08modified 2026-06-17

references (14)

External citations — patches, advisories, analysis.

scry

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