CVE-2026-42327 rust-openssl: undefined behavior in X509Ref::ocsp_responders for certificates with non-UTF-8 OCSP URLs
Attackers can trigger undefined behavior in rust-openssl by providing certificates with non-UTF-8 OCSP URLs, potentially leading to crashes or code execution.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-42327?
CVE-2026-42327 is a high-severity memory corruption vulnerability in rust-openssl, published on 14 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-20
Which versions are affected by CVE-2026-42327?
2 open source packages ship an affected version, including openssl.
| Package | Affected | Fixed in |
|---|---|---|
openssl crates.io | From 0.9.7 | 0.10.79 |
openssl crates.io | From 0.9.7 | 0.10.79 |
How do I fix CVE-2026-42327?
Upgrade openssl to 0.10.79 or later.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-42327 being exploited?
There is no known exploitation of CVE-2026-42327 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-42327, GHSA-xp3w-r5p5-63rr, MINI-3g7w-6vr9-65pc, MINI-4w5m-cfp6-xgrx, MINI-8r87-6f22-3x29, MINI-fj2c-w9hh-m5wq and 6 more.