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Not in CISA KEV

rust-openssl has undefined behavior in X509Ref::ocsp_responders for certificates with non-UTF-8 OCSP URLsGHSA-xp3w-r5p5-63rr

GHSA-xp3w-r5p5-63rr is a Improper Input Validation vulnerability in openssl. A fix is available for openssl — see the affected versions and patch details below.

Also known asCVE-2026-42327
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-xp3w-r5p5-63rr.

EPSS Exploitation Probability

via FIRST.org ↗
0.2%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs11th percentile — riskier than 11% of all scored CVEsHighest risk
0.00%0.24%0.47%0.71%0.0%0.2%Jun 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected
🦀openssl

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.

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.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🦀crates.ioopenssl≥ 0.9.7&&< 0.10.790.10.79cargo update -p openssl --precise 0.10.79

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for openssl, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update openssl to 0.10.79 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-xp3w-r5p5-63rr is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

`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.
O3 Security · Impact-Aware SCA

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rust-openssl has undefined behavior in X509Ref::ocsp_res…