cpp-httplib: CRLF injection via unvalidated HTTP trailer headers in chunked response writing

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-77341
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-28 00:18:15 UTC
Updated2026-08-28 00:18:15 UTC
Descriptioncpp-httplib is a C++ header-only HTTP/HTTPS library. In version 0.49.0, the chunked-response trailer output path writes trailer header names and values directly to the socket without validating them, allowing CRLF sequences in a trailer field to inject additional headers or split the HTTP response. Unlike every other header-writing path in the library, the trailer-writing code applies none of the field-name and field-value checks that reject carriage return and line feed, so an application that places attacker-influenced data into a chunked response trailer emits attacker-controlled CRLF onto the wire. This enables HTTP response splitting, letting an attacker forge response headers or inject a second response. This issue is fixed in version 0.50.0.

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:N/VI:L/VA:N/SC:L/SI:L/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

Problem Types: CWE-93 | CWE-113 | CWE-93 CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection') | 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:N/VI:L/VA:N/SC:L/SI:L/SA:N/E:X/C...
4.0CNADECLARED5.3MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N

CVSS v4.0 Breakdown

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

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Yhirose Cpp-httplib affected >= 0.49.0, < 0.50.0 Not specified

References

ReferenceSourceLinkTags
github.com/yhirose/cpp-httplib/security/advisories/GHSA-2r2h-jc8w-w66c [email protected] github.com
github.com/yhirose/cpp-httplib/commit/568d434e72fc51729d0ad33abffb181e5f... [email protected] github.com
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