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CVE-2026-28388 Detail

Description

Issue summary: When a delta CRL that contains a Delta CRL Indicator extension is processed a NULL pointer dereference might happen if the required CRL Number extension is missing. Impact summary: A NULL pointer dereference can trigger a crash which leads to a Denial of Service for an application. When CRL processing and delta CRL processing is enabled during X.509 certificate verification, the delta CRL processing does not check whether the CRL Number extension is NULL before dereferencing it. When a malformed delta CRL file is being processed, this parameter can be NULL, causing a NULL pointer dereference. Exploiting this issue requires the X509_V_FLAG_USE_DELTAS flag to be enabled in the verification context, the certificate being verified to contain a freshestCRL extension or the base CRL to have the EXFLAG_FRESHEST flag set, and an attacker to provide a malformed CRL to an application that processes it. The vulnerability is limited to Denial of Service and cannot be escalated to achieve code execution or memory disclosure. For that reason the issue was assessed as Low severity according to our Security Policy. 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.


Metrics

NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.
CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

References to Advisories, Solutions, and Tools

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URL Source(s) Tag(s)
https://github.com/openssl/openssl/commit/59c3b3158553ab53275bbbccca5cb305d591cf2e OpenSSL Software Foundation
https://github.com/openssl/openssl/commit/5a0b4930779cd2408880979db765db919da55139 OpenSSL Software Foundation
https://github.com/openssl/openssl/commit/602542f2c0c2d5edb47128f93eac10b62aeeefb3 OpenSSL Software Foundation
https://github.com/openssl/openssl/commit/a9d187dd1000130100fa7ab915f8513532cb3bb8 OpenSSL Software Foundation
https://github.com/openssl/openssl/commit/d3a901e8d9f021f3e67d6cfbc12e768129862726 OpenSSL Software Foundation
https://openssl-library.org/news/secadv/20260407.txt OpenSSL Software Foundation

Weakness Enumeration

CWE-ID CWE Name Source
CWE-476 NULL Pointer Dereference OpenSSL Software Foundation  

Change History

1 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2026-28388
NVD Published Date:
04/07/2026
NVD Last Modified:
04/07/2026
Source:
OpenSSL Software Foundation