{"cve":"CVE-2026-28388","nvd":{"published":"2026-04-07T22:16:20.863","modified":"2026-07-24T23:10:00.563","status":"Modified","description":"Issue summary: When a delta CRL that contains a Delta CRL Indicator extension\nis processed a NULL pointer dereference might happen if the required CRL\nNumber extension is missing.\n\nImpact summary: A NULL pointer dereference can trigger a crash which\nleads to a Denial of Service for an application.\n\nWhen CRL processing and delta CRL processing is enabled during X.509\ncertificate verification, the delta CRL processing does not check\nwhether the CRL Number extension is NULL before dereferencing it.\nWhen a malformed delta CRL file is being processed, this parameter\ncan be NULL, causing a NULL pointer dereference.\n\nExploiting this issue requires the X509_V_FLAG_USE_DELTAS flag to be enabled in\nthe verification context, the certificate being verified to contain a\nfreshestCRL extension or the base CRL to have the EXFLAG_FRESHEST flag set, and\nan attacker to provide a malformed CRL to an application that processes it.\n\nThe vulnerability is limited to Denial of Service and cannot be escalated to\nachieve code execution or memory disclosure. For that reason the issue was\nassessed as Low severity according to our Security Policy.\n\nThe FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this issue,\nas the affected code is outside the OpenSSL FIPS module boundary.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-476"],"references":["https://github.com/openssl/openssl/commit/59c3b3158553ab53275bbbccca5cb305d591cf2e","https://github.com/openssl/openssl/commit/5a0b4930779cd2408880979db765db919da55139","https://github.com/openssl/openssl/commit/602542f2c0c2d5edb47128f93eac10b62aeeefb3","https://github.com/openssl/openssl/commit/a9d187dd1000130100fa7ab915f8513532cb3bb8","https://github.com/openssl/openssl/commit/d3a901e8d9f021f3e67d6cfbc12e768129862726"],"products":["openssl:openssl"],"source":"nvd","synced_at":"2026-10-19T22:28:59.047572785+00:00"},"epss":{"cve":"CVE-2026-28388","score":0.00885,"percentile":0.5924,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}