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OpenSSL CVE-2026-28389

| EUVDEUVD-2026-19965 HIGH
NULL Pointer Dereference (CWE-476)
2026-04-07 openssl GHSA-7x88-9hgc-69gf
Denial Of Service Null Pointer Dereference OpenSSL
High
Disputed · 7.5 NVD
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Severity by source

Sources disagree (Low–High)
NVD PRIMARY
7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SUSE
HIGH
qualitative
Red Hat
5.9 LOW
qualitative

vuln.today treats the vendor’s rating as authoritative. A higher third-party CVSS (e.g. CISA-ADP) is shown for transparency but does not drive the headline severity.

CVSS VectorNVD

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

5
Re-analysis Queued
Apr 23, 2026 - 16:12 vuln.today
cvss_changed
EUVD ID Assigned
Apr 07, 2026 - 22:16 euvd
EUVD-2026-19965
Analysis Generated
Apr 07, 2026 - 22:16 vuln.today
Patch released
Apr 07, 2026 - 22:16 nvd
Patch available
CVE Published
Apr 07, 2026 - 22:00 nvd
HIGH 7.5

DescriptionCVE.org

Issue summary: During processing of a crafted CMS EnvelopedData message with KeyAgreeRecipientInfo a NULL pointer dereference can happen.

Impact summary: Applications that process attacker-controlled CMS data may crash before authentication or cryptographic operations occur resulting in Denial of Service.

When a CMS EnvelopedData message that uses KeyAgreeRecipientInfo is processed, the optional parameters field of KeyEncryptionAlgorithmIdentifier is examined without checking for its presence. This results in a NULL pointer dereference if the field is missing.

Applications and services that call CMS_decrypt() on untrusted input (e.g., S/MIME processing or CMS-based protocols) are vulnerable.

The FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.

AnalysisAI

Null pointer dereference in OpenSSL 1.0.2 through 3.6 CMS EnvelopedData processing crashes applications before authentication when KeyAgreeRecipientInfo messages lack optional parameters field. Unauthenticated remote attackers can trigger denial of service against S/MIME processors and CMS-based protocol handlers calling CMS_decrypt() on untrusted input. FIPS modules unaffected. Vendor-released patches available for all affected branches (1.0.2zp, 1.1.1zg, 3.0.20, 3.3.7, 3.4.5, 3.5.6, 3.6.2). Low observed exploitation activity; no public exploit identified at time of analysis.

Technical ContextAI

CWE-476 null pointer dereference occurs when CMS_decrypt() processes KeyEncryptionAlgorithmIdentifier within KeyAgreeRecipientInfo structures. Code unconditionally accesses optional parameters field without null-check validation. Failure occurs pre-authentication during ASN.1 parsing phase before cryptographic operations, enabling low-complexity network-based exploitation without privileges or user interaction per CVSS:3.1/AV:N/AC:L/PR:N/UI:N.

RemediationAI

Vendor-released patch: upgrade to OpenSSL 1.0.2zp, 1.1.1zg, 3.0.20, 3.3.7, 3.4.5, 3.5.6, or 3.6.2 per affected version branch. Upstream fixes available via commits f80f83bc5fd0, 16cea4188e0e, 785cbf7ea3b5, c6725634e089, 7b5274e81240. No workarounds identified; patching required. Prioritize internet-facing S/MIME gateways and services processing untrusted CMS data. Verify FIPS module usage if applicable (unaffected by this issue). Consult vendor advisory https://openssl-library.org/news/secadv/20260407.txt and Ubuntu security notice https://ubuntu.com/security/notices/USN-8155-1 for distribution-specific guidance. Validate patch deployment through regression testing of CMS EnvelopedData workflows.

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Vendor StatusVendor

SUSE

Severity: High
Product Status
Container suse/ltss/sle12.5/sles12sp5:8.5.219 Affected
Container suse/manager/4.3/proxy-httpd:4.3.17.9.76.9 Container suse/manager/4.3/proxy-squid:4.3.17.9.75.7 Container suse/manager/4.3/proxy-ssh:4.3.17.9.66.7 Affected
Container suse/manager/4.3/proxy-salt-broker:4.3.17.9.66.9 Container suse/manager/4.3/proxy-tftpd:4.3.17.9.66.8 Affected
Container suse/sl-micro/6.0/baremetal-os-container:2.1.3-6.157 Container suse/sl-micro/6.0/kvm-os-container:2.1.3-6.141 Container suse/sl-micro/6.0/rt-os-container:2.1.3-7.155 Affected
Container suse/sl-micro/6.0/base-os-container:2.1.3-7.124 Image SL-Micro Image SLE-Micro Image SLE-Micro-Azure Image SLE-Micro-BYOS Image SLE-Micro-BYOS-Azure Image SLE-Micro-BYOS-EC2 Image SLE-Micro-BYOS-GCE Image SLE-Micro-EC2 Image SLE-Micro-GCE Affected

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CVE-2026-28389 vulnerability details – vuln.today
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