NULL Pointer Dereference in OpenSSL Password-Based CMS Decryption
CVE-2026-42766 is a low-severity NULL pointer dereference in OpenSSL's password-based CMS decryption logic. A specially crafted password-encrypted CMS message can omit the optional PasswordRecipientInfo.keyDerivationAlgorithm field, which is permitted by the ASN.1 specification. During CMS decryption, the OpenSSL CMS implementation dereferences this field without first verifying that it is present. As a result, an application that processes attacker-supplied password-encrypted CMS content via the affected CMS decryption paths can crash. Reported affected versions are OpenSSL 4.0.0 before 4.0.1, 3.6.0 before 3.6.3, 3.5.0 before 3.5.7, 3.4.0 before 3.4.6, 3.0.0 before 3.0.21, 1.1.1 before 1.1.1zh, and 1.0.2 before 1.0.2zq. The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are stated to be unaffected because the vulnerable code lies outside the OpenSSL FIPS module boundary.
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Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
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Remediation
Patch, then assume compromise.
Exploits
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Affected products & vendors
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
17 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
An OpenSSL vulnerability addressed in Alpine Linux 3.22.5 and 3.23.5 as part of the June 9, 2026 OpenSSL advisory.
An OpenSSL vulnerability addressed in Alpine Linux 3.24.1 as part of the June 9, 2026 advisory.
A low-severity OpenSSL NULL pointer dereference in password-based CMS decryption caused by dereferencing an optional absent keyDerivationAlgorithm field, leading to denial of service.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.