CVE-2026-35189: Excessive Memory Allocation in Relative CRLDP Processing

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-29 · updated 2026-10-08
Weakness: CWE-770

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 memory allocations for a long time when such certificates are received. FIPS impact: no The affected code is outside the FIPS module boundary.

Affected products

OpenSSL: from 1.0.2 before 1.0.2zs; from 1.1.1 before 1.1.1zj; from 3.0.0 before 3.0.23; from 3.4.0 before 3.4.8; from 3.5.0 before 3.5.9; from 3.6.0 before 3.6.5 — fixed in 1.0.2zs, 1.1.1zj, 3.0.23, 3.4.8, 3.5.9, 3.6.5

How to fix

Upgrade to a fixed version: OpenSSL 1.0.2zs, 1.1.1zj, 3.0.23, 3.4.8. Check the vendor advisory for mitigations.

References

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