{"cve":"CVE-2021-4044","nvd":{"published":"2021-12-14T19:15:07.807","modified":"2026-06-17T04:18:56.683","status":"Modified","description":"Internally libssl in OpenSSL calls X509_verify_cert() on the client side to verify a certificate supplied by a server. That function may return a negative return value to indicate an internal error (for example out of memory). Such a negative return value is mishandled by OpenSSL and will cause an IO function (such as SSL_connect() or SSL_do_handshake()) to not indicate success and a subsequent call to SSL_get_error() to return the value SSL_ERROR_WANT_RETRY_VERIFY. This return value is only supposed to be returned by OpenSSL if the application has previously called SSL_CTX_set_cert_verify_callback(). Since most applications do not do this the SSL_ERROR_WANT_RETRY_VERIFY return value from SSL_get_error() will be totally unexpected and applications may not behave correctly as a result. The exact behaviour will depend on the application but it could result in crashes, infinite loops or other similar incorrect responses. This issue is made more serious in combination with a separate bug in OpenSSL 3.0 that will cause X509_verify_cert() to indicate an internal error when processing a certificate chain. This will occur where a certificate does not include the Subject Alternative Name extension but where a Certificate Authority has enforced name constraints. This issue can occur even with valid chains. By combining the two issues an attacker could induce incorrect, application dependent behaviour. Fixed in OpenSSL 3.0.1 (Affected 3.0.0).","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-835"],"references":["https://git.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=758754966791c537ea95241438454aa86f91f256","https://security.netapp.com/advisory/ntap-20211229-0003/","https://www.openssl.org/news/secadv/20211214.txt","https://git.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=758754966791c537ea95241438454aa86f91f256","https://security.netapp.com/advisory/ntap-20211229-0003/"],"products":["netapp:500f_firmware","netapp:a250_firmware","netapp:cloud_backup","netapp:e-series_performance_analyzer","netapp:h300e_firmware","netapp:h300s_firmware","netapp:h410c_firmware","netapp:h410s_firmware","netapp:h500e_firmware","netapp:h500s_firmware","netapp:h700e_firmware","netapp:h700s_firmware","netapp:ontap_select_deploy_administration_utility","netapp:snapcenter","nodejs:node.js","openssl:openssl"],"source":"nvd","synced_at":"2026-10-19T21:25:41.256909649+00:00"},"epss":{"cve":"CVE-2021-4044","score":0.50099,"percentile":0.98905,"date":"2026-11-01"},"kev":null,"osv":[{"id":"GHSA-mmjf-f5jw-w72q","url":"https://osv.dev/vulnerability/GHSA-mmjf-f5jw-w72q","summary":"Invalid handling of `X509_verify_cert()` internal errors in libssl","modified":"2024-12-16T15:27:05.176063Z","packages":[{"ecosystem":"crates.io","name":"openssl-src","purl":"pkg:cargo/openssl-src","ranges":[">=300.0.0 <300.0.4"],"fixed":["300.0.4"]}]},{"id":"RUSTSEC-2021-0129","url":"https://osv.dev/vulnerability/RUSTSEC-2021-0129","summary":"Invalid handling of `X509_verify_cert()` internal errors in libssl","modified":"2024-12-16T15:27:05.176063Z","packages":[{"ecosystem":"crates.io","name":"openssl-src","purl":"pkg:cargo/openssl-src","ranges":[">=300.0.0 <300.0.4"],"fixed":["300.0.4"]}]}],"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."]}