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CVE-2026-22245

Mastodon has SSRF Protection bypass

Published: Jan 8, 2026Updated: Jan 15, 2026 Sources: CVE List NVDCWE-918
7.5HIGH
NVD MITRE
EPSS Score
0.3%
Top 83.8%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
Not available

Description

Mastodon is a free, open-source social network server based on ActivityPub. By nature, Mastodon performs a lot of outbound requests to user-provided domains. Mastodon, however, has some protection mechanism to disallow requests to local IP addresses (unless specified in `ALLOWED_PRIVATE_ADDRESSES`) to avoid the "confused deputy" problem. The list of disallowed IP address ranges was lacking some IP address ranges that can be used to reach local IP addresses. An attacker can use an IP address in the affected ranges to make Mastodon perform HTTP requests against loopback or local network hosts, potentially allowing access to otherwise private resources and services. This is fixed in Mastodon v4.5.4, v4.4.11, v4.3.17 and v4.2.29.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:HI:NA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:NIntegrity
None
A:NAvailability
None
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Weaknesses

CWE-918

Affected Products

joinmastodon
oss-projectaka mastodon
mastodonOn-prem
Communications / messaging-chat
mastodon
oss-projectaka mastodon/mastodon
mastodonOn-prem
Communications / messaging-chat

Exploitability

Official Patch Available
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Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

2 techniques
Command and Control
Initial Access
View detailed technique mapping

References

https://github.com/mastodon/mastodon/commit/0f4e8a6240b5af1f2c3f34d2793d8610c6ef2aca
github.com
https://github.com/mastodon/mastodon/commit/17022907866710a72a1b1fc0a5ce9538bad1b4c3
github.com
https://github.com/mastodon/mastodon/commit/71ae4cf2cf5138ccdda64b1b1d665849b688686d
github.com
and 1 more references View all →

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