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OpenSSL CVE-2026-42771

| EUVDEUVD-2026-35488 MEDIUM
Out-of-bounds Read (CWE-125)
2026-06-09 GHSA-6fmj-jmjq-qcmg
OpenSSL Information Disclosure Buffer Overflow Red Hat
6.2
CVSS 3.1 · Vendor
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Severity by source

Vendor (CNA) PRIMARY
6.2 MEDIUM
AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SUSE
3.1 LOW
AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L
Red Hat
6.5 LOW
qualitative

Primary rating from Vendor (CNA).

CVSS VectorVendor

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

5
Source Code Evidence Fetched
Jun 09, 2026 - 20:28 vuln.today
Analysis Generated
Jun 09, 2026 - 20:28 vuln.today
CVSS changed
Jun 09, 2026 - 20:22 NVD
6.2 (MEDIUM)
CVE Published
Jun 09, 2026 - 11:43 nvd
UNKNOWN (no severity yet)
CVE Published
Jun 09, 2026 - 11:43 nvd
MEDIUM 6.2

Description PRE-NVD

Disclosed via GitHub release of openssl/openssl. NVD scoring and full description are pending.

AnalysisAI

Out-of-bounds read in OpenSSL 4.0.0's X509_VERIFY_PARAM_set1_email() function can crash applications performing email-based X.509 certificate verification when processing attacker-influenced email input, resulting in a denial-of-service condition. The vulnerability is scoped to OpenSSL 4.0.0 only and was patched in the June 9, 2026 security release (4.0.1), which bundled fixes for 18 CVEs. No public exploit identified at time of analysis and no CISA KEV listing.

Technical ContextAI

The affected function X509_VERIFY_PARAM_set1_email() is part of OpenSSL's X.509 certificate verification parameter API, used by applications that enforce email address constraints during certificate chain validation. CWE-125 (Out-of-Bounds Read) indicates the root cause is insufficient boundary checking when reading from a buffer while processing the email parameter - likely a missing or incorrect length validation allows the read pointer to advance past allocated memory. The CVSS vector AV:L indicates the vulnerable code path is only reachable in local execution contexts, meaning an attacker must either run code on the same host or influence input passed by a local application to this API call. Affected CPE: OpenSSL 4.0.0 (cpe:/a:openssl:openssl:4.0.0) as confirmed by EUVD-2026-35488.

RemediationAI

Upgrade to OpenSSL 4.0.1, which is the vendor-released patch that resolves CVE-2026-42771 and 17 additional CVEs in the same release. The official advisory is available at https://openssl-library.org/news/secadv/20260609.txt and the release at https://github.com/openssl/openssl/releases/tag/openssl-4.0.1. If immediate upgrade is not feasible, a compensating control is to audit and restrict application code paths that call X509_VERIFY_PARAM_set1_email() with externally sourced input, adding explicit length validation or input sanitization before passing email strings to the OpenSSL API. Applications that do not use email-based certificate verification constraints are not exposed to this specific code path and face no risk from this CVE.

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Vendor StatusVendor

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Severity: Low
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CVE-2026-42771 vulnerability details – vuln.today
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