🛡️ CVE-2026-21428
🟠 CVSS 7.5 — High ⚠️ Exploit Public CWE-93 NVD
7.5
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to version 0.30.0, the ``write_headers`` function does not check for CR & LF characters in user supplied headers, allowing untrusted header value to escape header lines. This vulnerability allows attackers to add extra headers, modify request body unexpectedly & trigger an SSRF attack. When combined with a server that supports http1.1 pipelining (springboot, python twisted etc), this can be used for server side request forgery (SSRF). Version 0.30.0 fixes this issue.

Details

Severity HIGH
CVSS Score 7.5
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
CWE CWE-93
Public Exploit ⚠️ Yes
Source NVD
Published 2026-01-01
Updated 2026-06-02
Modified 2026-01-06

Affected Packages

Software From version Fixed in
cpp-httplib 0.30.0

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