CVE-2026-66753 tiny-http 0.12.0 HTTP Response Splitting via Header Injection
Attackers can inject CRLF bytes into HTTP headers in tiny-http, enabling response splitting, cache poisoning, and session fixation attacks.
- 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-2026-66753?
CVE-2026-66753 is a medium-severity vulnerability in tiny-http, published on 28 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
tiny-http through 0.12.0 contains an HTTP header injection vulnerability that allows attackers to inject carriage return (0x0D) and line feed (0x0A) bytes into HTTP header values on both request and response sides due to insufficient validation in header parsing and serialization. Attackers can exploit this injection primitive to perform response splitting, cache poisoning, session fixation via Set-Cookie injection, security header override, and request smuggling against line-feed-tolerant backends.
Weakness: CWE-113
Which versions are affected by CVE-2026-66753?
How do I fix CVE-2026-66753?
No fix has been published for CVE-2026-66753 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-66753 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-66753 exists.
Public exploit code: 1 proofs of concept on GitHub.
Sources
Also known as DEBIAN-CVE-2026-66753, GHSA-5wm6-g4fr-88x8, UBUNTU-CVE-2026-66753.