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OpenSSL CVE-2026-35188

| EUVDEUVD-2026-35480 MEDIUM
Double Free (CWE-415)
2026-06-09 GHSA-vc8w-w49c-4jgj
Information Disclosure OpenSSL Red Hat
5.0
CVSS 3.1 · Vendor
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Severity by source

Vendor (CNA) PRIMARY
5.0 MEDIUM
AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L
vuln.today AI
5.0 MEDIUM

AV:N because the exploit path is a remote TLS connection; AC:H because OCSP stapling must be enabled and heap state must be suitable; PR:L because the attacker must control a server the victim connects to.

3.1 AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L
4.0 AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N
SUSE
6.6 MEDIUM
AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
Red Hat
5.9 MEDIUM
qualitative

Primary rating from Vendor (CNA).

CVSS VectorVendor

Attack Vector
Network
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
Low

Lifecycle Timeline

4
Source Code Evidence Fetched
Jul 23, 2026 - 17:12 vuln.today
Analysis Generated
Jul 23, 2026 - 17:12 vuln.today
CVE Published
Jun 09, 2026 - 11:43 github-releases
MEDIUM 5.0
CVE Published
Jun 09, 2026 - 11:43 nvd
UNKNOWN (no severity yet)

Description PRE-NVD

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

AnalysisAI

Double-free vulnerability in OpenSSL's OCSP stapled response verification allows remote attackers with low privilege to cause memory corruption affecting confidentiality, integrity, and availability. CVE-2026-35188 affects OpenSSL 4.0.0 (fixed in 4.0.1) and the 3.6.x branch (fixed in 3.6.3), and is one of seventeen CVEs addressed in the OpenSSL 4.0.1 security patch release published 2026-06-09. No public exploit and no active exploitation (CISA KEV) have been identified at time of analysis; however, the SSVC framework rates technical impact as 'total', flagging potential severity beyond the moderate CVSS base score.

Technical ContextAI

OpenSSL (CPE: cpe:2.3:a:openssl:openssl) is the world's most widely deployed cryptographic library, providing TLS/SSL, X.509 certificate handling, and numerous cryptographic primitives. OCSP stapling (RFC 6066) allows a TLS server to attach a pre-fetched OCSP revocation response to the TLS handshake, reducing client-side latency for certificate validation. The flaw maps to CWE-415 (Double Free): OpenSSL's internal OCSP stapled response checking routine frees the same memory region twice under specific processing conditions. Double-free bugs corrupt the heap allocator's internal state, which can lead to arbitrary code execution, process crashes, or information disclosure from heap memory - consistent with the C:L/I:L/A:L CVSS impact vector. The exact code path is confirmed by two NVD-referenced commits to the openssl/openssl and openssl/security repositories (commits 131145d and 78d0154), and the official security advisory at openssl-library.org/news/secadv/20260609.txt.

RemediationAI

Upgrade to OpenSSL 4.0.1 (for the 4.0.x branch) or OpenSSL 3.6.3 (for the 3.6.x branch), both confirmed as fixed releases per the vendor advisory at https://openssl-library.org/news/secadv/20260609.txt and the GitHub release at https://github.com/openssl/openssl/releases/tag/openssl-4.0.1. The upstream fix commits are 131145d25659e8749a9ed1afb383484854cffb78 and 78d0154cffda03aaaac63a087cc523a6b35fa8fd. As a compensating control where immediate patching is not possible, applications can disable OCSP stapling verification (via SSL_CTX_set_tlsext_status_cb or equivalent), which eliminates the vulnerable code path at the cost of losing revocation checking guarantees - this trade-off reduces security posture and should only be temporary. Operators using OpenSSL in shared libraries (e.g., via system packages) should apply OS-vendor security updates which will typically bundle the fixed version.

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Same weakness CWE-415 – Double Free

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Same technique Information Disclosure

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8.8

Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
SLES15-SP5-CHOST-BYOS-SAP-CCloud Not-Affected
SLES15-SP5-CHOST-BYOS-SAP-CCloud Not-Affected
SLES15-SP6-CHOST-BYOS Not-Affected
SLES15-SP6-CHOST-BYOS Not-Affected
SLES15-SP6-CHOST-BYOS-Aliyun Not-Affected

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CVE-2026-35188 vulnerability details – vuln.today
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