Description
LibreSSL ocspcheck through 4.4.0 contains a CRLF injection vulnerability that allows attackers to inject HTTP headers by embedding CR/LF sequences in a certificate's AIA OCSP URI path. Because url2host() copies the path without rejecting control characters and http_open() places it in the POST request line, attackers can inject headers or split OCSP requests sent to the responder host.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| OpenBSD | LibreSSL | ≤ 4.4.0 | — |
Advisories 1
- WID-SEC-2026-4202 LibreSSL: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 27, 2026
References
- https://github.com/openbsd/src/commit/6efdc4cce3fac9fa7208a9452f84de34c5a68e9f patch
- https://github.com/openbsd/src/commit/3adb7688a5bcfb675fa6d8b10e242022d620a23d patch
- https://github.com/openbsd/src/blob/17a8e44328ee2505d69723a126a390a526e50370/usr.sbin/ocspcheck/http.c#L344 technical-description
- https://github.com/openbsd/src/blob/17a8e44328ee2505d69723a126a390a526e50370/usr.sbin/ocspcheck/ocspcheck.c#L154 technical-description
- LibreSSL 4.4.0 Release Notes release-notes
- https://github.com/libressl/portable product
- VulnCheck Advisory: LibreSSL ocspcheck through 4.4.0 CRLF Injection via AIA OCSP URL Path third-party-advisory