CVE-2026-63074

medium CVSS 5.9 EPSS 0.5%

Issue summary: The OpenSSL Certificate Management Protocol (CMP) caches additional certificates (extraCerts) sent in a CMP message, but never expunges them (for instance if they are invalid). If a server reuses an OSSL_CMP_CTX frequently, this cache of extraCerts may grow unboundedly, and a malicious client may flood a CMP server with requests driving this growth. Impact summary: Users utilizing a CMP server that reuses a single OSSL_CMP_CTX for the lifetime of a server process may observe unbounded memory growth in the event a malicious client repeatedly sends requests containing unique extra certificates, which may lead to OOM conditions. CWE: CWE-770: Allocation of Resources Without Limits or Throttling Description: If a remote user sends CMP messages to a server with a list of extraCerts and the message is rejected, the extraCerts from the message remains in the server contexts untrusted certificate stack. This exposes servers with long lived ctx objects to Denial of Service attacks in which an attacker sends messages intending to be rejected with a large list of additional certificates repeatedly, forcing the server to store them indefinitely. The issue was fixed by...

Versions it affects

Software versions checked with the free lookup that CVE-2026-63074 applies to, and the release that fixes it where the sources name one.

openssl 3.0.11 fixed in 4.0.2 OpenSSL 3.5.7 fixed in 4.0.2 OpenSSL 4.0.1 fixed in 4.0.2

At a glance

Severity: Medium
CVSS base score: 5.9 out of 10
Known exploited: Not in CISA's catalogue of exploited vulnerabilities
EPSS: 0.5% probability of exploitation in the next 30 days, higher than 41% of scored vulnerabilities
Weakness: CWE-770
Published: 2026-08-25

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