← Vulnerability feed

Vulnerability record · CVE-2026-42765 · published 9 June 2026

CVE-2026-42765: Openssl null pointer dereference vulnerability

OOpenssl · Openssl

Issue summary: When a partial-chain certificate verification is enabled together with OCSP response checking for the whole chain, a NULL dereference will happen if the verified chain does not have a self-signed trusted anchor, crashing the process. Impact summary: A NULL pointer dereference can trigger a crash which leads to a Denial of Service for an application. When performing OCSP response checking for certificates in the verification chain, the code always tries to access the next certificate as the issuer. There is a check for a self-signed certificate. However with the partial chain verification enabled when the chain does not have a self-signed trusted anchor, the issuer will be NULL for the last certificate in the chain. A NULL pointer dereference then happens. This issue affects only applications which enable both OCSP verification of the certificate chain (X509_V_FLAG_OCSP_RESP_CHECK_ALL) and partial chain verification (X509_V_FLAG_PARTIAL_CHAIN) in the certificate verification. Both flags are disabled by default. For that reason, we have assigned Low severity to the issue. No FIPS modules are affected by this issue as the affected code is outside the OpenSSL FIPS module boundary.

7.5 CVSS 3.1 High EPSS 0.48% · top 61.3% CWE-476 · NULL pointer dereference
7.5CVSS 3.1 base score
0.48%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
3References
23 Jul 2026Last modified by NVD

Description

Issue summary: When a partial-chain certificate verification is enabled together with OCSP response checking for the whole chain, a NULL dereference will happen if the verified chain does not have a self-signed trusted anchor, crashing the process. Impact summary: A NULL pointer dereference can trigger a crash which leads to a Denial of Service for an application. When performing OCSP response checking for certificates in the verification chain, the code always tries to access the next certificate as the issuer. There is a check for a self-signed certificate. However with the partial chain verification enabled when the chain does not have a self-signed trusted anchor, the issuer will be NULL for the last certificate in the chain. A NULL pointer dereference then happens. This issue affects only applications which enable both OCSP verification of the certificate chain (X509_V_FLAG_OCSP_RESP_CHECK_ALL) and partial chain verification (X509_V_FLAG_PARTIAL_CHAIN) in the certificate verification. Both flags are disabled by default. For that reason, we have assigned Low severity to the issue. No FIPS modules are affected by this issue as the affected code is outside the OpenSSL FIPS module boundary.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/openssl/openssl/commit/14340b7fa1d444615486bc137014b064e64ec334 Patch
https://github.com/openssl/openssl/commit/eb345da18ce2216b2f3ade9c2bc23e068487fa97 Patch
https://openssl-library.org/news/secadv/20260609.txt Vendor Advisory

Track CVE-2026-42765 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

Start free Open in platform

Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

7.5CVE-2014-0160OpenSSL TLS/DTLS Heartbeat Extension Out-of-Bounds Read (Heartbleed)OpenSSL 1.0.1 before 1.0.1g mishandles Heartbeat Extension packets in its TLS and DTLS implementations, causing an out-of-bounds read of process memo…KEVEPSS 100%analysed10.0CVE-2009-3245Openssl improper input validation vulnerabilityOpenSSL before 0.9.8m does not check for a NULL return value from bn_wexpand function calls in (1) crypto/bn/bn_div.c, (2) crypto/bn/bn_gf2m.c, (3) c…EPSS 6.5%10.0CVE-2006-3738OpenSSL SSL_get_shared_ciphers buffer overflow via long cipher listOpenSSL versions before 0.9.7l and 0.9.8d contain a buffer overflow in the SSL_get_shared_ciphers function, triggered by a long list of ciphers. The …EPSS 49%analysed9.8CVE-2026-63073Openssl vulnerabilityIssue summary: OpenSSL CMP response validation passed an unexpected response sender distinguished name directly as the format string to `ERR_raise_da…EPSS 1.2%9.8CVE-2026-31789Openssl out-of-bounds write vulnerabilityIssue summary: Converting an excessively large OCTET STRING value to a hexadecimal string leads to a heap buffer overflow on 32 bit platforms. Impact…EPSS 0.33%9.8CVE-2022-2274OpenSSL 3.0.4 RSA AVX512IFMA memory corruptionOpenSSL 3.0.4 introduced a bug in the RSA implementation for X86_64 CPUs supporting AVX512IFMA instructions, causing 2048-bit private key operations …EPSS 46%analysed9.8CVE-2021-3711OpenSSL SM2 decryption buffer overflowOpenSSL's SM2 decryption code miscalculates the output buffer size needed by EVP_PKEY_decrypt(), so the first sizing call can return a value smaller …EPSS 88%analysed9.8CVE-2016-6309OpenSSL 1.1.0a statem use-after-free on realloc in TLS session handlingOpenSSL 1.1.0a's statem/statem.c fails to account for memory-block movement after a realloc call, leaving a dangling pointer that can be used after f…EPSS 70%analysed

Source: NIST National Vulnerability Database (record CVE-2026-42765), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.