Http4s: FollowRedirect middleware leaks credentials over https->http same-authority redirect
33Vexday Risk Score
No sign of exploitation. It has a public proof of concept.
ssvc Attendcvss 5.9epss 0.2%
from disclosure to weapon0 days
Published on NVDSep 15
1st PoCJun 28
exploitation probability
0.2%top 85% of all CVEs
observed exploitation
nono source reports it
1 public exploit(s)
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.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Affected products
http4s · http4spublic PoCs found — 1
githubgithub.com/c0gnit00/CVE-2026-69212★ 2⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.