The vulnerability arises when a TLS server calls SSL_set_SSL_CTX() to switch a connection to a different SSL_CTX partway through the handshake. The TLS connection records the number of certificate slots based on the original SSL_CTX, sizing an internal array accordingly. If the replacement SSL_CTX is aware of more provider signature algorithms than the original, the server may read and write beyond the end of this array when processing peer signature algorithms. This out-of-bounds access can cause heap corruption and process abort, leading to denial of service. The flaw requires differing provider signature algorithm counts between contexts, which typically involves separate library contexts or different loaded providers. Since the affected configuration is uncommon and the stale count hides corresponding certificates, the issue is considered low severity despite a CVSS score of 7.5. No FIPS modules are affected as the vulnerable code lies outside the FIPS boundary.

A remote peer can cause a small out-of-bounds read and, under certain conditions, a fixed-value out-of-bounds write on the server heap by exploiting this vulnerability. This can corrupt heap metadata and abort the server process, resulting in a denial of service. There is no impact on confidentiality or integrity, and no known exploits are currently in the wild. The issue only affects servers that call SSL_set_SSL_CTX() during handshake with differing provider signature algorithm counts between contexts.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, avoid configurations where SSL_set_SSL_CTX() is called during handshake to switch contexts with differing provider signature algorithm counts. Since the issue requires non-default configurations, reviewing server TLS context switching and provider setups can mitigate risk.