CVE-2021-3449 – NULL pointer deref in signature_algorithms processing

https://notcve.org/view.php?id=CVE-2021-3449

An OpenSSL TLS server may crash if sent a maliciously crafted renegotiation ClientHello message from a client. If a TLSv1.2 renegotiation ClientHello omits the signature_algorithms extension (where it was present in the initial ClientHello), but includes a signature_algorithms_cert extension then a NULL pointer dereference will result, leading to a crash and a denial of service attack. A server is only vulnerable if it has TLSv1.2 and renegotiation enabled (which is the default configuration). OpenSSL TLS clients are not impacted by this issue. All OpenSSL 1.1.1 versions are affected by this issue. • http://www.openwall.com/lists/oss-security/2021/03/27/1 http://www.openwall.com/lists/oss-security/2021/03/27/2 http://www.openwall.com/lists/oss-security/2021/03/28/3 http://www.openwall.com/lists/oss-security/2021/03/28/4 https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf https://cert-portal.siemens.com/productcert/pdf/ssa-772220.pdf https://git.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=fb9fa6b51defd48157eeb207f52181f735d96148 https://kb.pulse • CWE-476: NULL Pointer Dereference •