CVE-2026-42766: Possible NULL Dereference in Password-Based CMS Decryption

Published May 27, 2026
·
Updated

Issue summary: A specially crafted password-encrypted CMS message can trigger a NULL pointer dereference during CMS decryption.

Other sources

Possible NULL Dereference in Password-Based CMS Decryption

— Microsoft

Affected Software

11 affected componentsFixes available
OpenSSL OpenSSL
debian/openssl<=1.1.1w-0+deb11u1, <=1.1.1w-0+deb11u7, <=3.0.20-1~deb12u1, <=3.5.6-1~deb13u1, <=3.6.2-1
3.0.20-1~deb12u23.5.6-1~deb13u2
OpenSSL OpenSSL>=1.0.2<1.0.2zq
OpenSSL OpenSSL>=1.1.1<1.1.1zh
OpenSSL OpenSSL>=3.0.0<3.0.21
OpenSSL OpenSSL>=3.4.0<3.4.6
OpenSSL OpenSSL>=3.5.0<3.5.7
OpenSSL OpenSSL>=3.6.0<3.6.3
OpenSSL OpenSSL=4.0.0
Microsoft azl3 edk2 20240524git3e722403cd16-17<20240524git3e722403cd16-18
20240524git3e722403cd16-18
Microsoft azl3 openssl 3.3.5-5<3.3.7-3
3.3.7-3

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade debian/openssl to a version that resolves this vulnerability.

    Fixed in 3.0.20-1~deb12u2Fixed in 3.5.6-1~deb13u2
  2. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 20240524git3e722403cd16-18
  3. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 3.3.7-3
  4. Upgrade

    Upgrade OpenSSL to a version that resolves this vulnerability.

    Fixed in OpenSSL 1.0.2zq
  5. Upgrade

    Upgrade OpenSSL to a version that resolves this vulnerability.

    Fixed in OpenSSL 1.1.1zh
  6. Upgrade

    Upgrade OpenSSL to a version that resolves this vulnerability.

    Fixed in OpenSSL 3.0.21
  7. Upgrade

    Upgrade OpenSSL to a version that resolves this vulnerability.

    Fixed in OpenSSL 3.4.6
  8. Upgrade

    Upgrade OpenSSL to a version that resolves this vulnerability.

    Fixed in OpenSSL 3.5.7
  9. Upgrade

    Upgrade OpenSSL to a version that resolves this vulnerability.

    Fixed in OpenSSL 3.6.3
  10. Upgrade

    Upgrade OpenSSL to a version that resolves this vulnerability.

    Fixed in OpenSSL 4.0.1

Event History

May 27, 2026
Data Sourced
via Red Hat·02:18 PM
DescriptionSeverityAffected Software
Jun 9, 2026
CVE Published
via MITRE·04:03 PM
Data Sourced
via MITRE·04:03 PM
DescriptionWeakness
Data Sourced
via NVD·05:17 PM
DescriptionSeverityWeakness
Data Sourced
via NVD·05:17 PM
RemedyAffected Software
Data Sourced
via Ubuntu·08:07 PM
RemedyDescriptionSeverityAffected Software
Jun 10, 2026
Data Sourced
via Launchpad·08:09 PM
Description
Data Sourced
via Debian·08:09 PM
DescriptionAffected Software
Jun 13, 2026
Data Sourced
via Microsoft·08:05 AM
DescriptionSeverityWeaknessAffected Software
Updated
via Microsoft·08:05 AM
DescriptionSeverity
Updated
via Microsoft·08:05 AM
SeverityAffected Software

Frequently Asked Questions

1

What is the significance of CVE-2026-42766?

CVE-2026-42766 is a vulnerability that can lead to a NULL pointer dereference during password-based CMS decryption in OpenSSL.

2

What is the severity rating of CVE-2026-42766?

CVE-2026-42766 has a medium severity rating of 5.9 according to the CVSS 3.1 scoring system.

3

How can I mitigate CVE-2026-42766 in my system?

To mitigate CVE-2026-42766, ensure that you update OpenSSL to a version that includes the fix for this vulnerability.

4

Who is affected by CVE-2026-42766?

CVE-2026-42766 affects users of OpenSSL, specifically those utilizing password-based encryption for CMS messages.

5

Is there a workaround for CVE-2026-42766?

Currently, the best approach for CVE-2026-42766 is to apply the vendor's security updates, as there are no known effective workarounds.

Company

Resources

Contact

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