CVE-2026-69212

Http4s: FollowRedirect middleware leaks credentials over https->http same-authority redirect

State: Published
Severity: 5.9 Medium
Published: Sep 15, 2026
Updated: Sep 15, 2026
Reserved: Aug 3, 2026

Description

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, The FollowRedirect client middleware strips Authorization and Cookie headers only when a redirect changes authority, but authority comparison excludes the URI scheme. A same-authority redirect from HTTPS to HTTP therefore preserves credentials and transmits them over a plaintext connection. An attacker who can induce the downgrade and observe the network can capture those sensitive headers from applications using FollowRedirect. This issue is fixed in versions 0.23.35 and 1.0.0-M47.

Scores

CVSS	Score	Vector	Source
3.1	5.9 Medium	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N	GitHub_M

Weaknesses

CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
CWE-319 Cleartext Transmission of Sensitive Information

Affected Products

Product	Versions
http4shttp4s	< 0.23.35Affected >= 1.0.0-M1, < 1.0.0-M47Affected

References

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