Is CVE-2026-22246 in the CISA KEV catalog?

No. CVE-2026-22246 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-22246?

CVE-2026-22246 has a CVSS v3 base score of 6.5 (MEDIUM).

What is the EPSS score for CVE-2026-22246?

CVE-2026-22246 has an EPSS score of 0.23% (14th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-22246?

Upgrade mastodon to 4.5.4 or later.

CVE & CISA-KEV Catalog

CVE-2026-22246

MEDIUM

6.5

CVSS v3

NVD

Description

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.

CWE-201

How to fix

Remediation Available

mastodonNVD

Affected:>= 4.5.0, < 4.5.4Fixed in:4.5.4CVE-2026-22246derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityNone

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Exploit Intelligence

0.23%probability of exploitation in 30 days

14thpercentile

Low risk: more likely to be exploited than 14% of all known CVEs.

References

Patch3

Third-Party Advisory1

github.com

Related Vulnerabilities

Other CWE-201 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2017-16026	Medium	5.9	2.6%	-	Fix
CVE-2020-26085	Critical	9.9	2.5%	-	Fix
CVE-2017-2582	Medium	6.5	2.5%	-	Fix
CVE-2022-27779	Medium	5.3	2.4%	-	Fix
CVE-2024-32825	High	7.5	2.0%	-	-
CVE-2016-10518	High	7.5	2.0%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-01-22.