NULL pointer dereference in OpenSSL
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.004 (34.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 34th percentile — 34.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.004 · change: -0.001
Affected products
- OpenSSL — versions 4.0.0, 3.6.0, 3.5.0
Weakness classification (CWE)
References
- github.com/openssl/security/commit/61a86a8cd73546c9fea916f3d304c1293e05c046
- github.com/openssl/security/commit/665d5254083affde9982efca7c41dd01cacc8774
- github.com/openssl/security/commit/810b722f772652ad48042bcc7ab07e3414b11d0f
- github.com/openssl/security/commit/b90ff3b1bd33b1c18e6a09936d097c2eddef8873
- github.com/openssl/security/commit/e6f912907fc2ec82a0fd07aae55172c5e5e3d90d
- openssl-library.org/news/secadv/20260609.txt (vendor-advisory, Vendor Advisory)
- github.com/openssl/openssl/commit/61a86a8cd73546c9fea916f3d304c1293e05c046 (Patch, patch)
- github.com/openssl/openssl/commit/665d5254083affde9982efca7c41dd01cacc8774 (Patch, patch)
- github.com/openssl/openssl/commit/810b722f772652ad48042bcc7ab07e3414b11d0f (Patch, patch)
- github.com/openssl/openssl/commit/b90ff3b1bd33b1c18e6a09936d097c2eddef8873 (Patch, patch)
Frequently asked questions
- What is CVE-2026-42767?
- CVE-2026-42767 is a medium-severity vulnerability in OpenSSL, classified under NULL Pointer Dereference. CVSS score: 5.9/10. Published 2026-06-09.
- How severe is CVE-2026-42767?
- Medium severity. CVSS v3 base score is 5.9 out of 10.