CVE-2021-23841

Name of the Vulnerable Software and Affected Versions OpenSSL versions 1.1.1i and below OpenSSL versions 1.0.2x and below

Description The issue is related to the X509 issuer and serial hash() function, which attempts to create a unique hash value based on the issuer and serial number data contained within an X509 certificate. However, it fails to correctly handle any errors that may occur while parsing the issuer field, potentially resulting in a NULL pointer dereference and a crash, leading to a potential denial of service attack. This function is never directly called by OpenSSL itself, so applications are only vulnerable if they use this function directly and they use it on certificates that may have been obtained from untrusted sources. Additionally, calls to EVP CipherUpdate, EVP EncryptUpdate, and EVP DecryptUpdate may overflow the output length argument in some cases, causing applications to behave incorrectly or crash.

Recommendations For OpenSSL versions 1.1.1i and below, upgrade to OpenSSL 1.1.1j. For OpenSSL versions 1.0.2x and below, premium support customers should upgrade to 1.0.2y, while other users should upgrade to 1.1.1j. As a temporary workaround, consider avoiding the use of the X509 issuer and serial hash() function on certificates from untrusted sources until a patch is available.