LibreSSL ocspcheck through 4.4.0 Memory Exhaustion via Unbounded OCSP HTTP Response

Summary

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.

Remediation

1. Inventory every OpenBSD LibreSSL deployment, including staging.
2. No fixed version appears in the public sources yet. Check the references below and the vendor directly.

References

• Patchhttps://github.com/openbsd/src/commit/bf5da63f53179ef423d18c56d6da89eaefb56228
• Patchhttps://github.com/openbsd/src/commit/de4274c56c9ace88232591d4c919d79281a8de59
• Advisoryhttps://www.vulncheck.com/advisories/libressl-ocspcheck-through-4.4.0-memory-exhaustion-via-unbounded-ocsp-http-response
• Referencehttps://github.com/openbsd/src/blob/f6f428241d469cf434e60b73fc834d0448f068d5/usr.sbin/ocspcheck/http.c#L419
• Referencehttps://ftp.openbsd.org/pub/OpenBSD/LibreSSL/libressl-4.4.0-relnotes.txt
• Referencehttps://github.com/libressl/portable