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Medium

NULL Pointer Dereference in OpenSSL CRMF EncryptedValue Decryption

IdentifiersCVE-2026-42767CWE-476· NULL Pointer Dereference

CVE-2026-42767 is a NULL pointer dereference in OpenSSL’s CMP client handling of CRMF EncryptedValue data during processing of a CMP response. A malicious CMP server, or an attacker in a man-in-the-middle position, can send a crafted CMP response containing a CRMF CertRepMessage with an EncryptedValue structure in which the symmAlg field contains an algorithm OID but omits the parameters field. When the OpenSSL CMP client processes this malformed structure, it dereferences a NULL pointer and crashes. The issue affects applications that process untrusted CMP/CRMF messages via OpenSSL CMP client functionality. The vulnerable code is outside the OpenSSL FIPS module boundary, and the FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected.

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ANALYST BRIEF

Impact, mitigation & remediation

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Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation causes the CMP client application process to crash, resulting in denial of service. Based on the provided information, the impact is limited to application availability loss via process termination; no evidence is provided that this issue enables code execution, memory disclosure, or privilege escalation.

Mitigation

If you can’t patch tonight, do this now.

Until patched versions can be deployed, reduce exposure by preventing CMP client applications from processing CMP/CRMF messages from untrusted or unauthenticated servers, and minimize man-in-the-middle opportunities on CMP transport paths. Where operationally feasible, restrict CMP usage to trusted management networks and trusted endpoints. No specific code-level workaround beyond avoiding attacker-controlled CMP responses is provided in the available advisory material.

Remediation

Patch, then assume compromise.

Upgrade OpenSSL to a vendor-fixed release that includes the CVE-2026-42767 patch. The provided advisory context indicates fixes were issued in the June 9, 2026 OpenSSL security releases, with patched branches including OpenSSL 4.0.1, 3.6.3, 3.5.7, 3.4.6, and 3.0.21. Downstream consumers should also apply distribution-specific updates where applicable.
PUBLIC EXPLOITS

Exploits

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VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

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VendorProductType
FreebsdFreebsdapplication
OpenSSL Software FoundationOpensslapplication

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Associated malware

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Detection signatures

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