CVE-2026-63074Network attack vector

Service interruption via rejected extraCerts retention

Published Aug 25, 2026 · Updated Aug 25, 2026

Resource exhaustion in affected OpenSSL CMP servers allows remote attackers to cause an out-of-memory service interruption via rejected messages. The ossl_cmp_msg_check_update() failure path leaves message-supplied extraCerts in a reused OSSL_CMP_CTX untrusted-certificate stack rather than freeing them. Exposure requires an application operating as a CMP server to reuse one context for the process lifetime while accepting repeated requests with unique extra certificates; the documented consequence is unbounded memory growth and an out-of-memory condition.

CVSS severity5.9
Medium
EPSS probability0.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Resource exhaustion in affected OpenSSL CMP servers allows remote attackers to cause an out-of-memory service interruption via rejected messages. The ossl_cmp_msg_check_update() failure path leaves message-supplied extraCerts in a reused OSSL_CMP_CTX untrusted-certificate stack rather than freeing them. Exposure requires an application operating as a CMP server to reuse one context for the process lifetime while accepting repeated requests with unique extra certificates; the documented consequence is unbounded memory growth and an out-of-memory condition.

The record

CVE
CVE-2026-63074
Published
Aug 25, 2026
Updated
Aug 25, 2026
Vendor
OpenSSL Project
Product
OpenSSL
Classifications
CWE-770, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3.0.0 <3.0.22
  2. Affected versionversion=3.4.0 <3.4.7
  3. Affected versionversion=3.5.0 <3.5.8
  4. Affected versionversion=3.6.0 <3.6.4
  5. Affected versionversion=4.0.0 <4.0.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

OpenSSL Project · OpenSSLversion=3.0.0 <3.0.22; version=3.4.0 <3.4.7; version=3.5.0 <3.5.8; version=3.6.0 <3.6.4; version=4.0.0 <4.0.2

Published CVSS scores

5.9CISA ADPCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5Red HatCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499.003Application Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo