CVE-2026-42327: Rust-OpenSSL

High severity, CVSS 8.7. EPSS: 0.2% chance of exploitation in the next 30 days.

rust-openssl provides OpenSSL bindings for the Rust programming language. From 0.9.7 to before 0.10.79, X509Ref::ocsp_responders returns OCSP responder URLs from a certificate's AIA extension as OpensslString, whose Deref<Target = str> wraps the raw bytes with str::from_utf8_unchecked. OpenSSL does not enforce that the underlying IA5String is ASCII, so a certificate with non-UTF-8 bytes in its OCSP accessLocation causes safe Rust code to construct a &str that violates the UTF-8 invariant — resulting in undefined behavior. This vulnerability is fixed in 0.10.79.

Affected products

• Rust-OpenSSL Rust-OpenSSL: from 0.9.7, before 0.10.79 (fixed in 0.10.79)

Published 2026-05-14. Last modified 2026-06-17.