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Vulnerabilities

Vulnerability · CVE-2026-22245

Mastodon is a free, open-source social network server based on ActivityPub.

Published Jan 8, 2026 · catalog updated Jan 8, 2026 · Mastodon is a free,

Last checked Nov 6, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-22245. EPSS is 0.29%. Act only if a listed version of Mastodon is a free, is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Mastodon is a free,).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
High7.1
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.29%
Remediation
Version ranges on file
Affected products
vendor mastodon mastodon 4.4.0-beta.1, < 4.4.11

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 ) 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

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor mastodon mastodon 4.4.0-beta.1, < 4.4.114.4.0-beta.1, < 4.4.11

How to fix CVE-2026-22245

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-22245. EPSS is 0.29%. Act only if a listed version of Mastodon is a free, is installed.

Which versions are affected?

Compare what you have installed with mastodon mastodon 4.4.0-beta.1, < 4.4.11 4.4.0-beta.1, < 4.4.11. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.29%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Jan 8, 2026 · EUVD

    Detected

    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 ) to avoid the "confused deputy" problem. The list of disallowed IP address ranges was lacking some IP address ranges that can be

  2. Jan 8, 2026 · EUVD

    Updated

    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 ) to avoid the "confused deputy" problem. The list of disallowed IP address ranges was lacking some IP address ranges that can be

Sources

  • CVE.orgVulnerability recordCVE-2026-22245

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-22245

    30-day exploitation probability 0.29%

    first.org
  • EUVDVulnerability recordEUVD-2026-1674

    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 ) to avoi

    euvd.enisa.europa.eu

References

Freshness

Last verified in this catalog Nov 6, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSNov 6, 2026
  • CVE.orgOct 31, 2026
  • EUVDOct 30, 2026