CVE-2026-21428
7.5 · HIGHOverview
CVE-2026-21428 is a high-severity vulnerability affecting yhirose cpp-httplib. It was published on January 1, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical 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.
Remediation
Check the references section for vendor advisories and patches from yhirose. Update cpp-httplib to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| yhirose | cpp-httplib | >= 0, < 0.30.0 | Affected |
Frequently Asked Questions
What is CVE-2026-21428?
CVE-2026-21428 is a high-severity vulnerability affecting yhirose cpp-httplib. It was published on January 1, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).
How severe is CVE-2026-21428?
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-21428?
Check the references section for vendor advisories and patches from yhirose. Update cpp-httplib to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-21428?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-21428 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
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