CVEvulnerability

CVE-2026-33868

6.1 MEDIUM Published 2026-03-27 Modified 2026-06-17 Official page ↗
Status
Analyzed
Published
2026-03-27
Last modified
2026-06-17
Assigner
[email protected]
CVSS 3.1 ([email protected])
4.3 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
CVSS 3.1 ([email protected])
6.1 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Weaknesses
CWE-601

Description

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.

Affected configurations

• joinmastodon mastodon (< 4.3.21) • joinmastodon mastodon (>= 4.4.0 < 4.4.15) • joinmastodon mastodon (>= 4.5.0 < 4.5.8)

Related

Weakness · CWE (1)

  • CWE-601 URL Redirection to Untrusted Site weakness

References