Description
LibreSSL ocspcheck through 4.4.0 contains a cleartext transmission vulnerability because url2host() discards the OCSP URL scheme and http_alloc() only selects TLS for port 443. On-path network attackers can read OCSP requests sent to https responder URLs on non-443 ports, exposing certificate serial numbers, issuer hashes, and nonces.
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/0f7039667044d1cd252cc72134e499186da4da25 patch
- https://github.com/openbsd/src/blob/17a8e44328ee2505d69723a126a390a526e50370/usr.sbin/ocspcheck/http.c#L299 technical-description
- LibreSSL 4.4.0 Release Notes release-notes
- https://github.com/libressl/portable product
- VulnCheck Advisory: LibreSSL ocspcheck through 4.4.0 Cleartext Transmission of OCSP Requests via url2host() third-party-advisory