CVE-2026-42769Network attack vector

Trust-anchor substitution via incorrect CMP certificate chain

Published Jun 9, 2026 · Updated Jun 9, 2026

Improper certificate validation in OpenSSL allows remote authenticated users to replace a CMP client root CA via a crafted key-update response. OSSL_CMP_get1_rootCaKeyUpdate adds the untrusted newWithOld certificate instead of oldRoot to the validation chain, so only issuer names and algorithm identifiers are checked. Valid RA-level CMP message-protection credentials are required; accepted responses install an attacker-controlled self-signed certificate as the new trust anchor.

CVSS severity5.3
Medium
EPSS probability0.40%
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

Improper certificate validation in OpenSSL allows remote authenticated users to replace a CMP client root CA via a crafted key-update response. OSSL_CMP_get1_rootCaKeyUpdate adds the untrusted newWithOld certificate instead of oldRoot to the validation chain, so only issuer names and algorithm identifiers are checked. Valid RA-level CMP message-protection credentials are required; accepted responses install an attacker-controlled self-signed certificate as the new trust anchor.

The record

CVE
CVE-2026-42769
Published
Jun 9, 2026
Updated
Jun 9, 2026
Vendor
OpenSSL Project
Product
OpenSSL
Classifications
CWE-295, T1553.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 9, 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=3.4.0 <3.4.6
  2. Affected versionversion=3.5.0 <3.5.7
  3. Affected versionversion=3.6.0 <3.6.3
  4. Affected versionversion=4.0.0 <4.0.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

OpenSSL Project · OpenSSLversion=3.4.0 <3.4.6; version=3.5.0 <3.5.7; version=3.6.0 <3.6.3; version=4.0.0 <4.0.1

Published CVSS scores

5.3CISA-ADPCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-295Improper Certificate Validation
T1553.004Install Root Certificate

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