NULL Pointer Dereference When Processing a Delta CRL

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Summary

CVECVE-2026-28388
StatePUBLISHED
Assigneropenssl
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-07 22:16:20 UTC
Updated2026-04-08 21:27:00 UTC
DescriptionIssue 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.

Risk And Classification

EPSS: 0.000110000 probability, percentile 0.014190000 (date 2026-04-09)

Problem Types: CWE-476 | CWE-476 CWE-476 NULL Pointer Dereference

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA OpenSSL OpenSSL affected 3.6.0 3.6.2 semver Not specified
CNA OpenSSL OpenSSL affected 3.5.0 3.5.6 semver Not specified
CNA OpenSSL OpenSSL affected 3.4.0 3.4.5 semver Not specified
CNA OpenSSL OpenSSL affected 3.3.0 3.3.7 semver Not specified
CNA OpenSSL OpenSSL affected 3.0.0 3.0.20 semver Not specified
CNA OpenSSL OpenSSL affected 1.1.1 1.1.1zg custom Not specified
CNA OpenSSL OpenSSL affected 1.0.2 1.0.2zp custom Not specified

References

ReferenceSourceLinkTags
github.com/openssl/openssl/commit/602542f2c0c2d5edb47128f93eac10b62aeeefb3 [email protected] github.com
openssl-library.org/news/secadv/20260407.txt [email protected] openssl-library.org
github.com/openssl/openssl/commit/a9d187dd1000130100fa7ab915f8513532cb3bb8 [email protected] github.com
github.com/openssl/openssl/commit/59c3b3158553ab53275bbbccca5cb305d591cf2e [email protected] github.com
github.com/openssl/openssl/commit/d3a901e8d9f021f3e67d6cfbc12e768129862726 [email protected] github.com
github.com/openssl/openssl/commit/5a0b4930779cd2408880979db765db919da55139 [email protected] github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Igor Morgenstern (Aisle Research) (en)

CNA: Igor Morgenstern (Aisle Research) (en)

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