What is CVE-2026-63074?

CVE-2026-63074 is CMP Indefinite Cache Growth of ExtraCerts. The supplied enrichment data classifies it as Denial of Service mapped to CWE-770 CWE-770.

Which versions are affected?

Affected product and version evidence is listed in the product table above. Current public advisories should be checked for exact version scope before patch targeting is finalized.

Is there active exploitation?

Active exploitation is not confirmed from current sources for CVE-2026-63074. If exploitation is not confirmed from current sources, teams should document that status and continue monitoring KEV, vendor, and telemetry updates.

No. CVE-2026-63074 is not listed in CISA KEV in the supplied enrichment data. KEV status should be monitored because it can change after initial disclosure or after exploitation becomes publicly confirmed.

Is there a public exploit?

A public PoC is not confirmed from current sources for CVE-2026-63074. Public exploit or PoC availability should raise triage priority, especially for exposed or business-critical systems.

How can defenders detect it?

Start with Not reported where available. Look for vulnerability-class behavior, product errors, suspicious authentication events, exploit probes, and abnormal process activity based only on evidence that applies to the affected product.

How should teams prioritize it?

Prioritize CVE-2026-63074 using CVSS null, EPSS 0%, KEV status, public PoC status, and asset exposure. Internet-facing, privileged, or business-critical deployments should be handled first.

Are workarounds available?

The supplied mitigation guidance says to apply vendor patches and restrict external exposure until fixed. Fixed-version evidence is listed in the mitigation section above.

Which threat actors are linked publicly?

No public threat actor linkage is confirmed from current sources. Do not attribute exploitation to a threat actor unless the source evidence explicitly supports that linkage.

What should be done in the next 24 hours?

Identify exposed assets running affected vendor/product/version combinations. Prioritize based on EPSS, PoC availability, and external exposure. Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class. Open remediation tickets with affected assets, owners, evidence status, and detection coverage so decisions are traceable.

Denial of Service

CVE-2026-63074

CVE-2026-63074 — CMP Indefinite Cache Growth of ExtraCerts

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.

Published Aug 25, 2026Updated Aug 25, 2026Sources: NVD, OpenSSL (CNA), GitHub, SOCRadar CTI

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.

Exploitation

Unreported

no source claims exploitation

EPSS

ahead of 0% of scored CVEs

Affects

OpenSSL

5 products listed

CVSS base

Unscored

no source published a base score

Remediation

The vendor's own words where we have them.

Upgrade OpenSSL to a fixed release. Apply vendor patches per advisory and restrict external exposure of the affected component until patched.

First 24 hours

Ordered from the record's own fields — exposure first, because you cannot patch what you have not found.

Identify exposed assets running affected vendor/product/version combinations.
Prioritize based on EPSS, PoC availability, and external exposure.
Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class.

Affected scope

Vendor, product and version as the advisories word them.

Vendor	Product	Versions	Status
OpenSSL	OpenSSL	4.0.0 to < 4.0.2	Vulnerable
OpenSSL	OpenSSL	3.6.0 to < 3.6.4	Vulnerable
OpenSSL	OpenSSL	3.5.0 to < 3.5.8	Vulnerable
OpenSSL	OpenSSL	3.4.0 to < 3.4.7	Vulnerable
OpenSSL	OpenSSL	3.0.0 to < 3.0.22	Vulnerable

What this weakness leads to

MITRE's own consequences and mitigations for the weakness class — the authority's wording, not guidance derived from the CVSS vector.

MITRE

CWE-770 · Allocation of Resources Without Limits or Throttling

DoS: Resource Consumption (CPU)
DoS: Resource Consumption (Memory)
DoS: Resource Consumption (Other)

Mitigation: Clearly specify the minimum and maximum expectations for capabilities, and dictate which behaviors are acceptable when resource allocation reaches limits.

Weakness & attack patterns

CWE-770

Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.

CAPEC-125 · FloodingCAPEC-130 · Excessive AllocationCAPEC-147 · XML Ping of the DeathCAPEC-197 · XML Entity ExpansionCAPEC-229 · Serialized Data Parameter BlowupCAPEC-230 · XML Nested PayloadsCAPEC-231 · Oversized Serialized Data PayloadsCAPEC-469 · HTTP DoSCAPEC-482 · TCP FloodCAPEC-486 · UDP FloodCAPEC-487 · ICMP FloodCAPEC-488 · HTTP Flood

T1498.001Network Denial of Service: Direct Network Flood
T1499Endpoint Denial of Service
T1499.003Endpoint Denial of Service: Application Exhaustion Flood

Timeline

What happened to this CVE, newest first — with the readings a source repeats on a schedule counted underneath rather than listed.

2026
Initial · CVE published
Aug 25, 2026 · NVD

References

6 on the record

github.com/openssl/openssl/commit/01e567978a55fba18142a230380c31296049fae7
Exploit, Third Party Advisory, Mitre
github.com/openssl/openssl/commit/21a5d9658b0c66daace60e10ea18ff32a448de9f
Exploit, Third Party Advisory, Mitre
github.com/openssl/openssl/commit/74ae7f6df47a5767c1010b88c47507dfc5b32c46
Exploit, Third Party Advisory, Mitre
github.com/openssl/openssl/commit/75360af9650d4e0c82ba0050c5c9912cd79e54af
Exploit, Third Party Advisory, Mitre
github.com/openssl/openssl/commit/f636f9ca0fa1bae5b42f9e787f025c96fb09c43a
Exploit, Third Party Advisory, Mitre
openssl-library.org/news/secadv/20260825.txt
Vendor Advisory, Mitre

Elsewhere on this site

OpenSSLevery CVE for this vendor
Denial of Servicesame class
CWE-770other pages naming this weakness

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record1

What should defenders know first?

CVE-2026-63074 is CMP Indefinite Cache Growth of ExtraCerts, a unscored vulnerability affecting OpenSSL from OpenSSL. The current evidence does not list it in CISA KEV, and the exploit status is: Active exploitation is not confirmed from current sources for CVE-2026-63074. Public exploit evidence is: A public PoC is not confirmed from current sources for CVE-2026-63074. The affected-version evidence is listed in the key facts and affected products tables. Defenders should first verify whether exposed or business-critical assets run those versions, then apply vendor patches or mitigations, restrict reachable attack surface, and preserve logs for detection review. CVSS null describes technical severity, while EPSS 0% helps estimate near-term exploit likelihood; neither replaces asset context. Unknown fields should remain explicit in tickets, and threat actor, IOC, victimology, or payload claims should not be added unless a cited source supports them. Monitor CISA KEV, vendor advisories, NVD changes, public PoC repositories, and internal telemetry for update triggers.