Description
LibreSSL ocspcheck through 4.4.0 contains a memory exhaustion vulnerability that allows malicious OCSP responders to exhaust memory by sending unbounded HTTP responses. Attackers controlling the responder or intercepting plain HTTP AIA OCSP traffic can stream endless headers or body data to http_head_read() and http_body_read(), denying certificate status checks.
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/bf5da63f53179ef423d18c56d6da89eaefb56228 patch
- https://github.com/openbsd/src/commit/de4274c56c9ace88232591d4c919d79281a8de59 patch
- https://github.com/openbsd/src/blob/f6f428241d469cf434e60b73fc834d0448f068d5/usr.sbin/ocspcheck/http.c#L419 technical-description
- LibreSSL 4.4.0 Release Notes release-notes
- https://github.com/libressl/portable product
- VulnCheck Advisory: LibreSSL ocspcheck through 4.4.0 Memory Exhaustion via Unbounded OCSP HTTP Response third-party-advisory