Vulnerability · Published Jul 28, 2026 · Assigned by VulnCheck
CVE-2026-66746Rouille 0.4.0 - 3.6.2 HTTP Response Splitting via Header Injection
Medium 5.4
In plain English
A medium-severity security flaw in rouille from tomaka. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 28% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code.
Official description
Rouille 0.4.0 through 3.6.2 contains an HTTP response splitting vulnerability that allows remote attackers to inject arbitrary response headers by embedding carriage return (0x0D) or line feed (0x0A) bytes into attacker-controlled input. Attackers can exploit percent-decoded query parameters reflected into response headers or inject bare LF characters into Cookie header values that are interpolated directly into Set-Cookie response headers, enabling cache poisoning, session fixation, and security header override attacks such as bypassing CSP or CORS policies.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:14 | rust-rouille | no fix listed | DEBIAN-CVE-2026-66746 |
Affected products (as reported)
Weakness: CWE-113 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
References
- Researcher Disclosure technical-description, exploit
- https://www.vulncheck.com/advisories/rouille-http-response-splitting-via-header-injection third-party-advisory