MEDIUM
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).
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00004.html
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00011.html
http://packetstormsecurity.com/files/157527/OpenSSL-signature_algorithms_cert-Denial-Of-Service.html
http://seclists.org/fulldisclosure/2020/May/5
http://www.openwall.com/lists/oss-security/2020/04/22/2
https://github.com/irsl/CVE-2020-1967
https://kb.pulsesecure.net/articles/Pulse_Security_Advisories/SA44440
https://lists.apache.org/thread.html/[email protected]%3Cdev.tomcat.apache.org%3E
https://lists.apache.org/thread.html/[email protected]%3Cdev.tomcat.apache.org%3E
https://lists.apache.org/thread.html/[email protected]%3Cdev.tomcat.apache.org%3E
https://security.FreeBSD.org/advisories/FreeBSD-SA-20:11.openssl.asc
https://security.gentoo.org/glsa/202004-10
https://security.netapp.com/advisory/ntap-20200424-0003/
https://security.netapp.com/advisory/ntap-20200717-0004/
https://www.debian.org/security/2020/dsa-4661
https://www.openssl.org/news/secadv/20200421.txt
https://www.oracle.com/security-alerts/cpujul2020.html
https://www.oracle.com/security-alerts/cpuoct2020.html
https://www.synology.com/security/advisory/Synology_SA_20_05
https://www.synology.com/security/advisory/Synology_SA_20_05_OpenSSL
Source: MITRE
Published: 2020-04-21
Updated: 2020-10-20
Type: CWE-476
Base Score: 5
Vector: AV:N/AC:L/Au:N/C:N/I:N/A:P
Impact Score: 2.9
Exploitability Score: 10
Severity: MEDIUM
Base Score: 7.5
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Impact Score: 3.6
Exploitability Score: 3.9
Severity: HIGH