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CVE-2026-33868

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CVE-2026-33868

Published: Mar 27, 2026

Modified: Mar 31, 2026

PUBLISHED

CVSS v3.1

4.3

MEDIUM

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.

VendorProductVersions

mastodon

mastodon

affected
>= 4.5.0, < 4.5.8
affected
>= 4.4.0, < 4.4.15
affected
< 4.3.21

Weaknesses (CWE)

CWE-601

CVSS v3.1 Details

CVSS v3.1 Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

None

Integrity

Low

Availability

None

References

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