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

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.

Published: 2026-06-09 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-42766 is rated Low Risk (39.2/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.59%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-42766

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.07% 0.59% +0.52%
2 2026-06-10 — 0.07% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-42766

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.9 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.2 3.6 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2026-42766

GitHub Security Advisory for CVE-2026-42766

GHSA-58mv-qqmv-gqgv · Severity: medium — Issue summary: A specially crafted password-encrypted CMS message can trigger a NULL pointer...

OS Trackers for CVE-2026-42766

vendor priority summary link
debian not yet assigned CVE-2026-42766 not yet assigned priority: Debian including 1 source packages (openssl), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2026-42766
redhat low — https://access.redhat.com/security/cve/CVE-2026-42766
suse medium CVE-2026-42766 severity moderate: SUSE including 70 source package names (latest:libexpat1-2.7.1-4.1, latest:libopenssl3-3.1.4-slfo.1.1_10.1, …), 364 product×package rows across 68 product lines (Container suse/sl-micro/6.0/baremetal-os-container, Container suse/sl-micro/6.0/base-os-container, … (68 product lines)): First Fixed 240, Fixed 69, Known Not Affected 55. https://www.suse.com/security/cve/CVE-2026-42766/
ubuntu low CVE-2026-42766 low priority: Ubuntu including 5 source packages (edk2, nodejs, openssl, openssl-fips, openssl1.0), 35 status rows across 9 suites (bionic, focal, jammy, noble, questing, resolute, trusty, upstream, xenial): needs-triage 12, released 9, DNE 8, not-affected 5, needed 1. https://ubuntu.com/security/CVE-2026-42766

Affected software / configurations for CVE-2026-42766

Vendor Product Version Raw CPE
openssl openssl >= 1.0.2, < 1.0.2zq cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*
openssl openssl >= 1.1.1, < 1.1.1zh cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*
openssl openssl >= 3.0.0, < 3.0.21 cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*
openssl openssl >= 3.4.0, < 3.4.6 cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*
openssl openssl >= 3.5.0, < 3.5.7 cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*
openssl openssl >= 3.6.0, < 3.6.3 cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*
openssl openssl 4.0.0 cpe:2.3:a:openssl:openssl:4.0.0:-:*:*:*:*:*:*

References for CVE-2026-42766

cvelogic Threat Intelligence