Reference page — cumulative record through Monday, October 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2021-3450

CVE-2021-3450HIGH

OpenSSL OpenSSL — CA certificate check bypass with X509_V_FLAG_X509_STRICT

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   H   N   N  U  H  H  N    7.4   .1834   97.2     —

AFFECTED
  Product  Versions                                            Fixed
  OpenSSL  Fixed in OpenSSL 1.1.1k (Affected 1.1.1h-1.1.1j) –  —

TIMELINE
  Mar 19  Reserved by openssl
  Mar 25  Published (CNA: openssl)
  Oct 8   ENRICHED — CVE-2021-3450 (OpenSSL). Received CVSS 7.4 and CPE data from NVD.

CWE-295 · CNA: openssl · CVSS v3.1 · 24 references · NVD status: Modified

Description

The X509_V_FLAG_X509_STRICT flag enables additional security checks of the certificates present in a certificate chain. It is not set by default. Starting from OpenSSL version 1.1.1h a check to disallow certificates in the chain that have explicitly encoded elliptic curve parameters was added as an additional strict check. An error in the implementation of this check meant that the result of a previous check to confirm that certificates in the chain are valid CA certificates was overwritten. This effectively bypasses the check that non-CA certificates must not be able to issue other certificates. If a "purpose" has been configured then there is a subsequent opportunity for checks that the certificate is a valid CA. All of the named "purpose" values implemented in libcrypto perform this check. Therefore, where a purpose is set the certificate chain will still be rejected even when the strict flag has been used. A purpose is set by default in libssl client and server certificate verification routines, but it can be overridden or removed by an application. In order to be affected, an application must explicitly set the X509_V_FLAG_X509_STRICT verification flag and either not set a purpose for the certificate verification or, in the case of TLS client or server applications, override the default purpose. OpenSSL versions 1.1.1h and newer are affected by this issue. Users of these versions should upgrade to OpenSSL 1.1.1k. OpenSSL 1.0.2 is not impacted by this issue. Fixed in OpenSSL 1.1.1k (Affected 1.1.1h-1.1.1j).

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
March 19, 2021	Reserved	Reserved by openssl
March 25, 2021	Published	Published (CNA: openssl)
October 8, 2026	ENRICHED	ENRICHED — CVE-2021-3450 (OpenSSL). Received CVSS 7.4 and CPE data from NVD.

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
OpenSSL	OpenSSL	—	Fixed in OpenSSL 1.1.1k (Affected 1.1.1h-1.1.1j)	—

Weaknesses

CWE-295

References (24)

http://www.openwall.com/lists/oss-security/2021/03/27/1 [Mailing List, Third Party Advisory]
http://www.openwall.com/lists/oss-security/2021/03/27/2 [Mailing List, Third Party Advisory]
http://www.openwall.com/lists/oss-security/2021/03/28/3 [Mailing List, Third Party Advisory]
http://www.openwall.com/lists/oss-security/2021/03/28/4 [Mailing List, Third Party Advisory]
https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf [Third Party Advisory]
https://git.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=2a40b7bc7b94dd7de897a74571e7024f0cf0d63b
https://kb.pulsesecure.net/articles/Pulse_Security_Advisories/SA44845 [Third Party Advisory]
https://kc.mcafee.com/corporate/index?page=content&id=SB10356 [Third Party Advisory]
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CCBFLLVQVILIVGZMBJL3IXZGKWQISYNP/
https://mta.openssl.org/pipermail/openssl-announce/2021-March/000198.html [Mailing List, Vendor Advisory]
https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0013 [Third Party Advisory]
https://security.FreeBSD.org/advisories/FreeBSD-SA-21:07.openssl.asc [Third Party Advisory]
https://security.gentoo.org/glsa/202103-03 [Third Party Advisory]
https://security.netapp.com/advisory/ntap-20210326-0006/ [Third Party Advisory]
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-openssl-2021-GHY28dJd [Third Party Advisory]
https://www.openssl.org/news/secadv/20210325.txt [Vendor Advisory]
https://www.oracle.com//security-alerts/cpujul2021.html [Patch, Third Party Advisory]
https://www.oracle.com/security-alerts/cpuApr2021.html [Patch, Third Party Advisory]
https://www.oracle.com/security-alerts/cpuapr2022.html [Patch, Third Party Advisory]
https://www.oracle.com/security-alerts/cpujul2022.html [Patch, Third Party Advisory]
https://www.oracle.com/security-alerts/cpuoct2021.html [Patch, Third Party Advisory]
https://www.tenable.com/security/tns-2021-05 [Third Party Advisory]
https://www.tenable.com/security/tns-2021-08 [Third Party Advisory]
https://www.tenable.com/security/tns-2021-09 [Third Party Advisory]

Authoritative record: CVE-2021-3450 at cve.org

Vendors: openssl

Weaknesses: CWE-295

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2021-3450 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Monday, October 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.