CVE & CISA-KEV Catalog

CVE-2026-66746

MEDIUM
5.4
CVSS v3
NVD

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.

How to fix

No published remediation has been found for this vulnerability's affected products yet.

Mitigation guidance may be in the linked vendor advisories in the References section below.

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CVSS v3 Vector

Exploitability

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionRequired
ScopeUnchanged

Impact

ConfidentialityLow
IntegrityLow
AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

Exploit Intelligence

0.24%probability of exploitation in 30 days
15thpercentile

Low risk: more likely to be exploited than 15% of all known CVEs.

References

Other references2

Related Vulnerabilities

Other CWE-113 vulnerabilities, ordered by exploit likelihood. View all

CVESeverityCVSSEPSSExploitedFix
CVE-2022-37436Medium5.358%-Fix
CVE-2024-52875High8.830%--
CVE-2016-5699Medium6.110%-Fix
CVE-2016-8024High8.18.7%--
CVE-2017-17742Medium5.35.6%-Fix
CVE-2016-5325Medium6.14.1%-Fix

Common questions

How do I fix CVE-2026-66746?

No published fix for CVE-2026-66746 has been found yet. Check the linked vendor advisories for guidance as it becomes available.

Is CVE-2026-66746 being actively exploited?

Not that we know of. CVE-2026-66746 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.24% is the estimated probability that it will be exploited in the next 30 days. That is higher than 15% of all scored CVEs.

How severe is CVE-2026-66746?

CVE-2026-66746 has a CVSS v3 base score of 5.4, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-30.