🛡️ CVE-2026-42766 — openssl

🟡 CVSS 5.9 — Medium ✅ No Known Exploit CWE-476 NVD
5.9
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Issue summary: A specially crafted password-encrypted CMS message

can trigger a NULL pointer dereference during CMS decryption.

Impact summary: This NULL pointer dereference leads to an application crash

and a Denial of Service.

The CMS PasswordRecipientInfo.keyDerivationAlgorithm field is defined as

OPTIONAL in the ASN.1 specification and may therefore be absent in specially

crafted inputs. During the password-based CMS decryption the OpenSSL

CMS implementation dereferences this field without first checking whether it

was present.

An attacker who supplies such a CMS message to an application performing

password-based CMS decryption can trigger an application crash, leading to

a Denial of Service.

Applications that process password-encrypted CMS messages may be affected.

The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this

issue, as the affected code is outside the OpenSSL FIPS module boundary.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is high, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

Weakness class

CVE-2026-42766 is classified as CWE-476: NULL Pointer Dereference. A pointer that can be null is used without a check, crashing the process.

Affected software

CVE-2026-42766 is recorded against 2 packages.

  • openssl
  • unknown

Timeline and source

Published on 9 June 2026 and last revised on 23 July 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

github.com
github.com
github.com
github.com
github.com
openssl-library.org

CVE-2026-42766 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity MEDIUM
CVSS Score 5.9
CVSS Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE CWE-476
Public Exploit ✅ No
Source NVD
Published 2026-06-09
Updated 2026-08-11
Modified 2026-07-23

Affected Packages

Software From version Fixed in
openssl — —
unknown — —

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