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rust-openssl: undefined behavior in X509Ref::ocsp_responders for certificates with non-UTF-8 OCSP URLs

Type: advisorySources: OSV

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 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.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-42327
Confirmed fixed CVEs
Not specified
Updated in this feed
4 Nov 2026, 16:38 UTC · Revision 1

Source evidence

rust-openssl: undefined behavior in X509Ref::ocsp_responders for certificates with non-UTF-8 OCSP URLs

core-osv · Original source

Published 14 May 2026, 20:17 UTC

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 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.

osv:CVE-2026-42327
Complete source record
{
  "id": "33658e114b30923173637c4b4f30352a0cb5fe4dac9190182a35da60fe4d94df",
  "url": "https://osv.dev/vulnerability/CVE-2026-42327",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "rust-openssl: undefined behavior in X509Ref::ocsp_responders for certificates with non-UTF-8 OCSP URLs",
    "summary": "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 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.",
    "evidence": "osv:CVE-2026-42327",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-42327",
      "aliases": [
        "CVE-2026-42327",
        "GHSA-xp3w-r5p5-63rr"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "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"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/rust-openssl/rust-openssl",
              "type": "GIT",
              "events": [
                {
                  "introduced": "06065ddcee2abd5304a0aacb9643b925d504bb8b"
                },
                {
                  "fixed": "649f2d9e37f3aa701e20bd8ab5cd7eb5afa0a90f"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0.9.7"
                      },
                      {
                        "fixed": "0.10.79"
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                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.10.79"
                      }
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                    "source": "DESCRIPTION"
                  }
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          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-42327.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:37.395679743Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42327.json",
        "https://github.com/rust-openssl/rust-openssl/security/advisories/GHSA-xp3w-r5p5-63rr",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-42327"
      ],
      "provider_metadata": {
        "cwe_ids": [
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        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42327.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-42327",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 504772,
  "published_at": "2026-05-14T20:17:39.923+00:00"
}