CVE-2026-63074: CMP Indefinite Cache Growth of ExtraCerts
Vulnerability summary
CVE-2026-63074 is a medium (CVSS 5.9) vulnerability in openssl. EPSS estimates a 0.59% chance of exploitation in the next 30 days, higher than 48.1% of scored vulnerabilities.
Not severe (CVSS 5.9, network access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 16 · Related 12Timeline
- 25-08-2026PublishedVulnerability first disclosed.
- 25-08-2026Last modifiedVulnerability information updated.
Description
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 removing the added extra certs if the message is rejected, using the same method as when the context is configured to not do caching at all. FIPS impact: no As the CMP code lives outside the FIPS module boundary, no FIPS modules are affected by this CVE.
CVSS metrics
7 scores · 7 sources · 1 version- OSV · AlpineEcosystem advisory · calculated5.9MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · UbuntuEcosystem advisory · calculated5.9MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated5.9MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · ChainguardEcosystem advisory · calculated5.9MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- NVDNIST5.9MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · WolfiEcosystem advisory · calculated5.9MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.59%
Chance of exploitation in the next 30 days
Percentile
48%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.59% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.
Chainguard14 products
- eco-python-openssl-4< 4.0.2-r0
- eco-python-openssl-4-pyca< 4.0.2-r0
- eco-python-openssl-4-pyca-dev< 4.0.2-r0
- openssl-3.5< 3.5.8-r0
- openssl-3.5-libcrypto< 3.5.8-r0
Ubuntu5 products
- edk2All versions (No fix recorded)
- edk2-hweAll versions (No fix recorded)
- nodejsAll versions (No fix recorded)
- openssl< 3.0.2-0ubuntu1.29 | All versions (No fix recorded) | < 3.0.2-0ubuntu1.29+Fips1 | < 3.0.13-0ubuntu3.15 | < 3.5.5-1ubuntu3.4
- openssl-fipsAll versions (No fix recorded) | < 3.0.13-0ubuntu3.15+Fips1
Wolfi3 products
- openssl-4.0< 4.0.2-r0
- openssl-4.0-libcrypto< 4.0.2-r0
- openssl-4.0-libssl< 4.0.2-r0
Alpine1 product
- openssl≥ 3.0.0, < 3.5.8-r0
Debian1 product
- openssl< 3.0.22-1~deb12u1 | < 3.5.7-1~deb13u2 | < 3.6.4-1
Openssl1 product
- openssl≥ 3.0.0, < 3.0.22 | ≥ 3.4.0, < 3.4.7 | ≥ 3.5.0, < 3.5.8 | ≥ 3.6.0, < 3.6.4 | ≥ 4.0.0, < 4.0.2
6 vendors · 25 products
