High severity · published May 14, 2026
CVE-2026-42327
rust-openssl: undefined behavior in X509Ref::ocsp_responders for certificates with non-UTF-8 OCSP URLs
8.7
CVSS
0.2%
EPSS
No
On KEV
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.
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 11% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
RU
rust-openssl · rust-openssl
>= 0.9.7, < 0.10.79 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-42327
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-42327
github.com
https://github.com/rust-openssl/rust-openssl/security/advisories/GHSA-xp3w-r5p5-63rr
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