CVE-2026-77341: Yhirose Cpp-Httplib

Medium severity, CVSS 5.3. EPSS: 0.5% chance of exploitation in the next 30 days.

cpp-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.

Affected products

• Yhirose Cpp-Httplib: from 0.49.0, before 0.50.0 (fixed in 0.50.0)

Published 2026-08-28. Last modified 2026-09-09.