CVE-2026-42767

Description

Issue summary: An attacker-controlled CMP (Certificate Management Protocol) server could trigger a NULL pointer dereference in a CMP client application. Impact summary: A NULL pointer dereference causes a crash of the application and a Denial of Service. An attacker controlling a CMP server (or acting as a man-in-the-middle) could craft a CMP response containing a CRMF (Certificate Request Message Format) CertRepMessage with an EncryptedValue structure where the symmAlg field has an algorithm OID but no parameters field. When the OpenSSL CMP client processes this response, the NULL dereference occurs, causing a crash of the CMP client. Applications that process untrusted CMP/CRMF 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.

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CVSS v3.1 Score

5.9

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS — Exploit Prediction

0.0035

Probability of exploitation

0.27%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-476 CWE-476

Affected Products

Vendor	Product	Versions
openssl	openssl	3.0.0 — 3.0.21
openssl	openssl	3.4.0 — 3.4.6
openssl	openssl	3.5.0 — 3.5.7
openssl	openssl	3.6.0 — 3.6.3
openssl	openssl	All

References

Advisories & Patches

https://github.com/openssl/openssl/commit/61a86a8cd73546c9fea916f3d304c1293e05c046 https://github.com/openssl/openssl/commit/665d5254083affde9982efca7c41dd01cacc8774 https://github.com/openssl/openssl/commit/810b722f772652ad48042bcc7ab07e3414b11d0f https://github.com/openssl/openssl/commit/b90ff3b1bd33b1c18e6a09936d097c2eddef8873 https://github.com/openssl/openssl/commit/e6f912907fc2ec82a0fd07aae55172c5e5e3d90d https://openssl-library.org/news/secadv/20260609.txt

Frequently Asked Questions

What is CVE-2026-42767? +

Issue summary: An attacker-controlled CMP (Certificate Management Protocol) server could trigger a NULL pointer dereference in a CMP client application. Impact summary: A NULL pointer dereference causes a crash of the application and a Denial of Service. An attacker controlling a CMP server (or acting as a man-in-the-middle) could craft a CMP response containing a CRMF (Certificate Request Message Format) CertRepMessage with an EncryptedValue structure where the symmAlg field has an algorithm OID but no parameters field. When the OpenSSL CMP client processes this response, the NULL dereference occurs, causing a crash of the CMP client. Applications that process untrusted CMP/CRMF 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. It has a CVSS v3.1 base score of 5.9 (MEDIUM).

How severe is CVE-2026-42767? +

CVE-2026-42767 has a CVSS v3.1 score of 5.9 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0035, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-42767? +

CVE-2026-42767 affects products from openssl, specifically: openssl. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-42767? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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