Categories
CVE-2026-33868

Mastodon has a GET-Based Open Redirect via '/web/%2F<domain>'

Summary

Mastodon has a GET-Based Open Redirect via '/web/%2F<domain>'

Original description

The description as published by the source.

Mastodon is a free, open-source social network server based on ActivityPub. Prior to versions 4.5.8, 4.4.15, and 4.3.21, an unauthenticated Open Redirect vulnerability (CWE-601) exists in the /web/* route due to improper handling of URL-encoded path segments. An attacker can craft a specially encoded URL that causes the application to redirect users to an arbitrary external domain, enabling phishing attacks and potential OAuth credential theft. The issue occurs because URL-encoded slashes (%2F) bypass Rails path normalization and are interpreted as host-relative redirects. Versions 4.5.8, 4.4.15, and 4.3.21 patch the issue.

Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV

Affected packages

Bitnami mastodon
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"4.3.21"},{"introduced":"4.4.0"},{"fixed":"4.4.15"},{"introduced":"4.5.0"},{"fixed":"4.5.8"}]}]

References

We use cookies for analytics and ad measurement. This setting applies to all Game co., Ltd. sites. Details