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CVE-2026-35189

5.3 · MEDIUM

Issue summary: A certificate with many nameRelativeToCRLIssuer CRL distribution points causes disproportionate heap growth when OpenSSL caches X.509 extensions.

Published Sep 29, 2026opensslCWE-770EPSS 0.32%

Overview

CVE-2026-35189 is a medium-severity vulnerability affecting openssl openssl. It was published on September 29, 2026 and has a CVSS 3.1 base score of 5.3 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.3, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

Issue summary: A certificate with many nameRelativeToCRLIssuer CRL

distribution points causes disproportionate heap growth when OpenSSL caches

X.509 extensions.

Impact summary: Receiving a crafted certificate from a malicious peer can lead

to significant memory pressure and possible Denial of Service in clients or

in servers that solicit client certificates.

CWE: CWE-770: Allocation of Resources Without Limits or Throttling

Description: A certificate or a set of certificates that fits under the limit for

size of certificates accepted from the peer (~100 KiB) can result in allocation

of several hundred MiB of resident memory on the receiving side

during a normal TLS handshake. This may be enough to crash the client or

server, if multiple concurrent connections lead to similarly large memory

allocations.

The fix postpones processing of the CRL distribution points extensions in

certificates to the time when the processed value is required for CRL processing.

This avoids keeping large

Remediation

Check the references section for vendor advisories and patches from openssl. Update openssl to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

Affected products

VendorProductVersionsStatus
opensslopenssl>= 1.0.2, < 1.0.2zsAffected

References

GitHubgithub.com/openssl/openssl/commit/2b93c73b2c70ddc4c61c5e4bfaaa6bd71379eb84GitHubgithub.com/openssl/openssl/commit/3842516cc15e8b2cf55747011045e77547e71d89GitHubgithub.com/openssl/openssl/commit/8e0efc7549b7ff8246d40e585e3fd604f728473fGitHubgithub.com/openssl/openssl/commit/c72ae182cac17a82e4246c6ecd4e9c4ec3586ec9Refopenssl-library.org/news/secadv/20260929.txt

How CyberStrike helps

Frequently asked questions

What is CVE-2026-35189?

CVE-2026-35189 is a medium-severity vulnerability affecting openssl openssl. It was published on September 29, 2026 and has a CVSS 3.1 base score of 5.3 (MEDIUM).

How severe is CVE-2026-35189?

This vulnerability has a CVSS 3.1 base score of 5.3, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-35189?

Check the references section for vendor advisories and patches from openssl. Update openssl to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-35189?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-35189 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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