CVE-2021-3450

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).

• CWE-295

• http://www.openwall.com/lists/oss-security/2021/03/27/1Mailing List, Third Party Advisory
• http://www.openwall.com/lists/oss-security/2021/03/27/2Mailing List, Third Party Advisory
• http://www.openwall.com/lists/oss-security/2021/03/28/3Mailing List, Third Party Advisory
• http://www.openwall.com/lists/oss-security/2021/03/28/4Mailing List, Third Party Advisory
• https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdfThird Party Advisory
• https://git.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=2a40b7bc7b94dd7de897a74571e7024f0cf0d63b
• https://kb.pulsesecure.net/articles/Pulse_Security_Advisories/SA44845Third Party Advisory
• https://kc.mcafee.com/corporate/index?page=content&id=SB10356Third 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.htmlMailing List, Vendor Advisory
• https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0013Third Party Advisory
• https://security.FreeBSD.org/advisories/FreeBSD-SA-21:07.openssl.ascThird Party Advisory
• https://security.gentoo.org/glsa/202103-03Third 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-GHY28dJdThird Party Advisory
• https://www.openssl.org/news/secadv/20210325.txtVendor Advisory
• https://www.oracle.com//security-alerts/cpujul2021.htmlPatch, Third Party Advisory
• https://www.oracle.com/security-alerts/cpuApr2021.htmlPatch, Third Party Advisory
• https://www.oracle.com/security-alerts/cpuapr2022.htmlPatch, Third Party Advisory
• https://www.oracle.com/security-alerts/cpujul2022.htmlPatch, Third Party Advisory
• https://www.oracle.com/security-alerts/cpuoct2021.htmlPatch, Third Party Advisory
• https://www.tenable.com/security/tns-2021-05Third Party Advisory
• https://www.tenable.com/security/tns-2021-08Third Party Advisory
• https://www.tenable.com/security/tns-2021-09Third Party Advisory
• http://www.openwall.com/lists/oss-security/2021/03/27/1Mailing List, Third Party Advisory
• http://www.openwall.com/lists/oss-security/2021/03/27/2Mailing List, Third Party Advisory
• http://www.openwall.com/lists/oss-security/2021/03/28/3Mailing List, Third Party Advisory
• http://www.openwall.com/lists/oss-security/2021/03/28/4Mailing List, Third Party Advisory
• https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdfThird Party Advisory
• https://git.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=2a40b7bc7b94dd7de897a74571e7024f0cf0d63b
• https://kb.pulsesecure.net/articles/Pulse_Security_Advisories/SA44845Third Party Advisory
• https://kc.mcafee.com/corporate/index?page=content&id=SB10356Third 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.htmlMailing List, Vendor Advisory
• https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0013Third Party Advisory
• https://security.FreeBSD.org/advisories/FreeBSD-SA-21:07.openssl.ascThird Party Advisory
• https://security.gentoo.org/glsa/202103-03Third 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-GHY28dJdThird Party Advisory
• https://www.openssl.org/news/secadv/20210325.txtVendor Advisory
• https://www.oracle.com//security-alerts/cpujul2021.htmlPatch, Third Party Advisory
• https://www.oracle.com/security-alerts/cpuApr2021.htmlPatch, Third Party Advisory
• https://www.oracle.com/security-alerts/cpuapr2022.htmlPatch, Third Party Advisory
• https://www.oracle.com/security-alerts/cpujul2022.htmlPatch, Third Party Advisory
• https://www.oracle.com/security-alerts/cpuoct2021.htmlPatch, Third Party Advisory
• https://www.tenable.com/security/tns-2021-05Third Party Advisory
• https://www.tenable.com/security/tns-2021-08Third Party Advisory
• https://www.tenable.com/security/tns-2021-09Third Party Advisory

Published

Mar 25, 2021

Last Modified

Jun 17, 2026

Status

Modified

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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