CVE-2026-23961

mediumpriority · track · 0OT risk · elevatedEPSS 0.004 · 38 %ileEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.44% (38th) EPSS

CVSS 5.3 · 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 allows server administrators to suspend remote users to prevent interactions. However, some logic errors allow already-known posts from such suspended users to appear in timelines if boosted. Furthermore, under certain circumstances, previously-unknown posts from suspended users can be processed. This issue allows old posts from suspended users to occasionally end up on timelines on all Mastodon versions. Additionally, on Mastodon versions from v4.5.0 to v4.5.4, v4.4.5 to v4.4.11, v4.3.13 to v4.3.17, and v4.2.26 to v4.2.29, remote suspended users can partially bypass the suspension to get new posts in. Mastodon versions v4.5.5, v4.4.12, v4.3.18 are patched.

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-863US

affected products (9)

Products and version ranges known to be affected.

mastodon mastodon≤ < 4.3.18enisa_euvdEU
mastodon mastodon4.4.0, → 4.4.12enisa_euvdEU
mastodon mastodon4.5.0, → 4.5.5enisa_euvdEU
joinmastodon mastodon< 4.3.18nvdUScpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*
joinmastodon mastodon4.4.0 → 4.4.12nvdUScpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*
joinmastodon mastodon4.5.0 → 4.5.5nvdUScpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*
Bitnami mastodon< 4.3.18osvUSpkg:bitnami/mastodon
Bitnami mastodon4.4.0 → 4.4.12osvUSpkg:bitnami/mastodon
Bitnami mastodon4.5.0 → 4.5.5osvUSpkg:bitnami/mastodon

advisories (1)

Vendor and ecosystem advisories describing this.

BIT-mastodon-2026-23961Mastodon may allow a remote suspension bypass2026-02-03vendor · osvUS
Mastodon is a free, open-source social network server based on ActivityPub. Mastodon allows server administrators to suspend remote users to prevent interactions. However, some logic errors allow already-known posts from such suspended users to appear in timelines if boosted. Furthermore, under certain circumstances, previously-unknown posts from suspended users can be processed. This issue allows old posts from suspended users to occasionally end up on timelines on all Mastodon versions. Additionally, on Mastodon versions from v4.5.0 to v4.5.4, v4.4.5 to v4.4.11, v4.3.13 to v4.3.17, and v4.2.26 to v4.2.29, remote suspended users can partially bypass the suspension to get new posts in. Mastodon versions v4.5.5, v4.4.12, v4.3.18 are patched.

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 2026-01-22modified 2026-06-17

references (13)

External citations — patches, advisories, analysis.

scry

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