--- title: "CVE-2020-1967: Segmentation fault in SSL_check_chain | CubePath" description: "Server or client applications that call the SSL_check_chain() function during or after a TLS 1.3 handshake may crash due to a NULL pointer dereference…" language: en source: https://cubepath.com/security/cve/CVE-2020-1967 --- # CVE-2020-1967: Segmentation fault in SSL_check_chain | CubePath ## Description Server or client applications that call the SSL\_check\_chain() function during or after a TLS 1.3 handshake may crash due to a NULL pointer dereference as a result of incorrect handling of the "signature\_algorithms\_cert" TLS extension. The crash occurs if an invalid or unrecognised signature algorithm is received from the peer. This could be exploited by a malicious peer in a Denial of Service attack. OpenSSL version 1.1.1d, 1.1.1e, and 1.1.1f are affected by this issue. This issue did not affect OpenSSL versions prior to 1.1.1d. Fixed in OpenSSL 1.1.1g (Affected 1.1.1d-1.1.1f). Official description from the CVE record, published by openssl. Copyright © 1999-2026 The MITRE Corporation. See [/security/cve/legal](https://cubepath.com/security/cve/legal) for the CVE license. [View the record on cve.org](https://www.cve.org/CVERecord?id=CVE-2020-1967) ## Key data ### EPSS Exploit Prediction Scoring System by FIRST: an estimate of the probability that exploitation activity will be observed in the next 30 days. Score 0.53336 (53.3% probability) Percentile 99.0% Scores of Nov 10, 2026 Model v2026.06.15 ### CISA assessment as of Oct 8, 2026 Stakeholder-Specific Vulnerability Categorization (SSVC) decision points added by CISA. Automatable yes Technical impact partial ## Affected products Products listed in the CVE record, as the CNA published them. - OpenSSL - affected: Fixed in OpenSSL 1.1.1g (Affected 1.1.1d-1.1.1f) ## References Links listed in the CVE record. They lead to other sites, which CubePath does not control. - [FreeBSD-SA-20:11](https://security.FreeBSD.org/advisories/FreeBSD-SA-20:11.openssl.asc) (security.freebsd.org) vendor-advisory - [DSA-4661](https://www.debian.org/security/2020/dsa-4661) (debian.org) vendor-advisory - [\[oss-security\] 20200422 \[CVE-2020-1967\] OpenSSL 1.1.1d+ Segmentation fault in SSL\_check\_chain](http://www.openwall.com/lists/oss-security/2020/04/22/2) (openwall.com) mailing-list - [\[tomcat-dev\] 20200422 Time for Tomcat Native 1.2.24?](https://lists.apache.org/thread.html/r9a41e304992ce6aec6585a87842b4f2e692604f5c892c37e3b0587ee%40%3Cdev.tomcat.apache.org%3E) (lists.apache.org) mailing-list - [\[tomcat-dev\] 20200422 Re: Time for Tomcat Native 1.2.24?](https://lists.apache.org/thread.html/r66ea9c436da150683432db5fbc8beb8ae01886c6459ac30c2cea7345%40%3Cdev.tomcat.apache.org%3E) (lists.apache.org) mailing-list - [\[tomcat-dev\] 20200423 Re: Time for Tomcat Native 1.2.24?](https://lists.apache.org/thread.html/r94d6ac3f010a38fccf4f432b12180a13fa1cf303559bd805648c9064%40%3Cdev.tomcat.apache.org%3E) (lists.apache.org) mailing-list - [GLSA-202004-10](https://security.gentoo.org/glsa/202004-10) (security.gentoo.org) vendor-advisory - [FEDORA-2020-fcc91a28e8](https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XVEP3LAK4JSPRXFO4QF4GG2IVXADV3SO/) (lists.fedoraproject.org) vendor-advisory - [FEDORA-2020-da2d1ef2d7](https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DDHOAATPWJCXRNFMJ2SASDBBNU5RJONY/) (lists.fedoraproject.org) vendor-advisory - [20200501 CVE-2020-1967: proving sigalg != NULL](http://seclists.org/fulldisclosure/2020/May/5) (seclists.org) mailing-list - [FEDORA-2020-d7b29838f6](https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EXDDAOWSAIEFQNBHWYE6PPYFV4QXGMCD/) (lists.fedoraproject.org) vendor-advisory - [openSUSE-SU-2020:0933](http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00004.html) (lists.opensuse.org) vendor-advisory - [openSUSE-SU-2020:0945](http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00011.html) (lists.opensuse.org) vendor-advisory - [oracle.com/security-alerts/cpujul2020.html](https://www.oracle.com/security-alerts/cpujul2020.html) - [tenable.com/security/tns-2020-03](https://www.tenable.com/security/tns-2020-03) - [openssl.org/news/secadv/20200421.txt](https://www.openssl.org/news/secadv/20200421.txt) - [git.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=eb…](https://git.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=eb563247aef3e83dda7679c43f9649270462e5b1) - [kb.pulsesecure.net/articles/Pulse\_Security\_Advisories/SA444…](https://kb.pulsesecure.net/articles/Pulse%5FSecurity%5FAdvisories/SA44440) - [security.netapp.com/advisory/ntap-20200424-0003](https://security.netapp.com/advisory/ntap-20200424-0003/) - [synology.com/security/advisory/Synology\_SA\_20\_05\_OpenSSL](https://www.synology.com/security/advisory/Synology%5FSA%5F20%5F05%5FOpenSSL) - [github.com/irsl/CVE-2020-1967](https://github.com/irsl/CVE-2020-1967) - [packetstormsecurity.com/files/157527/OpenSSL-signature\_algo…](http://packetstormsecurity.com/files/157527/OpenSSL-signature%5Falgorithms%5Fcert-Denial-Of-Service.html) - [synology.com/security/advisory/Synology\_SA\_20\_05](https://www.synology.com/security/advisory/Synology%5FSA%5F20%5F05) - [tenable.com/security/tns-2020-04](https://www.tenable.com/security/tns-2020-04) - [oracle.com/security-alerts/cpuoct2020.html](https://www.oracle.com/security-alerts/cpuoct2020.html) - [security.netapp.com/advisory/ntap-20200717-0004](https://security.netapp.com/advisory/ntap-20200717-0004/) - [oracle.com/security-alerts/cpujan2021.html](https://www.oracle.com/security-alerts/cpujan2021.html) - [tenable.com/security/tns-2020-11](https://www.tenable.com/security/tns-2020-11) - [oracle.com/security-alerts/cpuApr2021.html](https://www.oracle.com/security-alerts/cpuApr2021.html) - [tenable.com/security/tns-2021-10](https://www.tenable.com/security/tns-2021-10) - [oracle.com//security-alerts/cpujul2021.html](https://www.oracle.com//security-alerts/cpujul2021.html) - [oracle.com/security-alerts/cpuoct2021.html](https://www.oracle.com/security-alerts/cpuoct2021.html) ## Timeline 1. ID reserved Dec 3, 2019 2. Record published Apr 21, 2020 3. Record last updated Oct 8, 2026 ## Look up another CVE ## About CubePath CubePath is a cloud provider with data centers in Europe and the United States. It offers VPS, bare metal servers and DDoS protection. [Cloud VPS](https://cubepath.com/vps) [DDoS protection](https://cubepath.com/ddos-protection) Data from the CVE Program (MITRE), CISA KEV and FIRST EPSS. CVSS is owned by FIRST and used by permission. Not affiliated with or endorsed by MITRE, CISA or FIRST. Data as of Nov 10, 2026, 20:01 UTC. [Sources and licenses](https://cubepath.com/security/cve/legal)