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CVE-2026-22245

HIGH
7.5

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.

CVE Details

CVSS v3.1 Score7.5
SeverityHIGH
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Attack VectorNETWORK
ComplexityLOW
Privileges RequiredNONE
User InteractionNONE
Published1/8/2026
Last Modified1/15/2026
Sourcenvd
Honeypot Sightings0

Affected Products

joinmastodon:mastodon

Weaknesses (CWE)

CWE-918

References

https://github.com/mastodon/mastodon/commit/0f4e8a6240b5af1f2c3f34d2793d8610c6ef2aca(security-advisories@github.com)
https://github.com/mastodon/mastodon/commit/17022907866710a72a1b1fc0a5ce9538bad1b4c3(security-advisories@github.com)
https://github.com/mastodon/mastodon/commit/71ae4cf2cf5138ccdda64b1b1d665849b688686d(security-advisories@github.com)
https://github.com/mastodon/mastodon/security/advisories/GHSA-xfrj-c749-jxxq(security-advisories@github.com)

IOC Correlations

No correlations recorded

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