Quick answers
- Is CVE-2026-66746 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-66746 being exploited in the wild.
- How severe is CVE-2026-66746?
- Medium severity, with a CVSS score of 5.4, published 28 July 2026.
- Which products and versions are affected?
- Tomaka Rouille 0.4.0 through 3.6.2.
- Is there a fix for CVE-2026-66746?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-66746 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-66746?
- Check whether you run Tomaka Rouille at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
Rouille versions 0.4.0 through 3.6.2 are vulnerable to HTTP response splitting (CWE-113) due to improper neutralization of CRLF sequences (0x0D and 0x0A) in HTTP headers. The vulnerability occurs when percent-decoded query parameters or unvalidated Cookie header values are interpolated directly into response headers like Set-Cookie. A remote attacker can exploit this by providing input containing carriage return or line feed characters, allowing them to terminate the current header and inject arbitrary new headers or a second response body. This can lead to cache poisoning, session fixation, and the bypass of security mechanisms such as Content Security Policy (CSP) or Cross-Origin Resource Sharing (CORS). Exploitation typically requires some level of user interaction to trigger the malicious request.
Affected products
- tomaka rouille 0.4.0 through 3.6.2
Timeline
- 2026-07-28: disclosed
- 2026-07-28: advisory