CVE-2026-66746: 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)
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.
Details
Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-66746
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Low exploitation riskCVE-2026-667460.24% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 15% of all scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-66746 | coverage & exploitation status | NVD · CVE.org |
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