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Vulnerability record · CVE-2026-42327 · published 14 May 2026

CVE-2026-42327: Improper input validation vulnerability

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.

8.7 CVSS 4.0 High EPSS 0.21% · top 89.8% CWE-20 · Improper input validation Deferred
8.7CVSS 4.0 base score
0.21%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
1References
17 Jun 2026Last modified by NVD

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.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

LinkTags
https://github.com/rust-openssl/rust-openssl/security/advisories/GHSA-xp3w-r5p5-63rr

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Source: NIST National Vulnerability Database (record CVE-2026-42327), CISA KEV, FIRST EPSS (scores of 2026-09-28). This page is refreshed as NVD updates the record.