Rouille 0.4.0 - 3.6.2 HTTP Response Splitting via Header Injection

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-66746
StatePUBLISHED
AssignerVulnCheck
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-28 16:20:16 UTC
Updated2026-07-30 16:41:25 UTC
DescriptionRouille 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.

Risk And Classification

Primary CVSS: v4.0 5.3 MEDIUM from [email protected]

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS: 0.002410000 probability, percentile 0.154080000 (date 2026-07-31)

Problem Types: CWE-113 | CWE-113 Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary5.3MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/C...
4.0CNACVSS5.3MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
3.1[email protected]Secondary5.4MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
3.1CNACVSS5.4MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
Passive
Confidentiality
Low
Integrity
Low
Availability
None
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Tomaka Rouille affected 0.4.0 3.6.2 semver Not specified

References

ReferenceSourceLinkTags
www.vulncheck.com/advisories/rouille-http-response-splitting-via-header-injection [email protected] www.vulncheck.com
github.com/theopaid/HTTP-Response-Splitting-via-Unvalidated-Response-Hea... [email protected] github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Theodosis Paidakis (en)

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