CVE-2026-69211 Http4s: Set-Cookie rendering does not escape attribute delimiters
Attackers can inject cookie attributes or split headers via unvalidated input in Http4s, weakening cookie security and potentially enabling header injection.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-69211?
CVE-2026-69211 is a medium-severity vulnerability in http4s, published on 15 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, ResponseCookie.render writes attacker-influenced name, content, domain, path, and extension values without neutralizing semicolons or control characters. An application that constructs a ResponseCookie from unvalidated input can therefore emit injected cookie attributes such as Domain, Path, or SameSite, widening cookie scope or weakening protections, and control characters may enable header splitting on permissive backends. The patch strips control characters from all five fields and strips semicolons from name, content, domain, and path while retaining the extension delimiter behavior. This issue is fixed in versions 0.23.35 and 1.0.0-M47.
Which versions are affected by CVE-2026-69211?
How do I fix CVE-2026-69211?
No fix has been published for CVE-2026-69211 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-69211 being exploited?
There is no known exploitation of CVE-2026-69211 in the wild and no public exploit code.
Sources
Also known as GHSA-7qh7-rghh-698h.