HTTP response splitting in Cpp-httplib - CVE-2026-77341
Published: August 25, 2026
Vulnerability identifier: #VU145122
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-77341
CWE-ID: CWE-113
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to inject arbitrary HTTP response headers.
The vulnerability exists due to improper neutralization of crlf sequences in HTTP trailer headers in the done_with_trailer lambda within write_content_chunked() when writing chunked response trailers containing attacker-controlled input. A remote attacker can supply crafted input containing crlf characters that is reflected into trailer fields to inject arbitrary HTTP response headers.
Exploitation requires an application to reflect attacker-controlled data into chunked response trailers via DataSink::done_with_trailer().
Affected software
Cpp-httplib
How to mitigate CVE-2026-77341
Install security update from vendor's website.
Cpp-httplib - update to 0.50.0