Is this vulnerability remotely exploitable over the internet?

Yes. An attacker who can supply or influence URLs that Mastodon fetches remotely can attempt to exploit this issue, provided the server has network access to internal resources via the overlooked IP ranges.

What level of access does an attacker need to exploit this?

The attacker generally needs the ability to cause Mastodon to perform outbound requests to attacker-controlled or attacker-chosen domains or URLs. This may be achievable through normal federation behavior or other features where user input results in remote resource fetching.

What is the safest general fix pattern for developers?

The most robust pattern is to enforce a centralized, strict allowlist or comprehensive denylist on all outbound HTTP requests, validating the final resolved IP address (including CNAME chains) against a well-maintained set of safe networks, and blocking local, private, and metadata address spaces by default.

Severity:

HIGH RISK

(7.5)

Server-Side Request Forgery (CWE-918) in Mastodon Outbound Request Filtering

CVE-2026-22245

Published:

Jan 8, 2026

Status:

Analyzed

Summary

Affected Context

Exploit Preconditions

Why This Happens

Potential Impact

General Mitigation Guidance

How Teams Detect Issues Like This

Frequently Asked Questions

Source

NDV

Recent Vulnerabilities

CWE-306

CRITICAL RISK

CRITICAL

(9.8)

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Account Takeover / Loss of Account Control

February 17, 2026

CWE-77;CWE-78

HIGH RISK

HIGH

(7.3)

OS Command Injection (CWE-78) in node-sonos-http-api TTS Provider for macOS

Remote Code Execution on the Server Host

February 17, 2026

Vulnerability Type

Category:

Server-Side Request Forgery (SSRF)

CWE:

CWE-918

Impact:

Unauthorized Access to Internal Services via SSRF

Severity:

HIGH RISK

(7.5)

CVSS Version:

3.1

Vulnerability Type

Category:

Server-Side Request Forgery (SSRF)

CWE:

CWE-918

Impact:

Unauthorized Access to Internal Services via SSRF

Severity:

HIGH RISK

(7.5)

CVSS Version:

3.1

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Made with Love in San Francisco

355 Bryant St. San Francisco, CA 94107, USA

Ask AI for summary of CodeAnt

Server-Side Request Forgery (CWE-918) in Mastodon Outbound Request Filtering

Summary

Affected Context

Exploit Preconditions

Why This Happens

Potential Impact

General Mitigation Guidance

How Teams Detect Issues Like This

Frequently Asked Questions

Source

Recent Vulnerabilities

CRITICAL RISK

CRITICAL

(9.8)

Missing Authentication for Forgot-Password Email Change API (CWE-306)

HIGH RISK

HIGH

(7.3)

OS Command Injection (CWE-78) in node-sonos-http-api TTS Provider for macOS

Vulnerability Type

Vulnerability Type

Vulnerability Type

Vulnerability Type

Catch This CVE While Code Is Being Written

Ship clean & secure code faster

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