CVE-2023-40217
MediumCVSS 5.3Exploitation Probability (EPSS)
Elevated risk51th percentile - higher than 51% of all known CVEs
Summary
An issue was discovered in Python before 3.8.18, 3.9.x before 3.9.18, 3.10.x before 3.10.13, and 3.11.x before 3.11.5, affecting servers using TLS client authentication. If a TLS server-side socket is closed quickly, data may still be readable from the socket buffer without authentication.
Risk Assessment
Organizations may be at risk of unauthorized access to data that can be read from the socket buffer, potentially leading to information security breaches.
Recommendation
It is recommended to update Python to the latest version to mitigate this vulnerability and to monitor TLS-using servers for potential incidents.
Original NVD description (English source)
An issue was discovered in Python before 3.8.18, 3.9.x before 3.9.18, 3.10.x before 3.10.13, and 3.11.x before 3.11.5. It primarily affects servers (such as HTTP servers) that use TLS client authentication. If a TLS server-side socket is created, receives data into the socket buffer, and then is closed quickly, there is a brief window where the SSLSocket instance will detect the socket as "not connected" and won't initiate a handshake, but buffered data will still be readable from the socket buffer. This data will not be authenticated if the server-side TLS peer is expecting client certificate authentication, and is indistinguishable from valid TLS stream data. Data is limited in size to the amount that will fit in the buffer. (The TLS connection cannot directly be used for data exfiltration because the vulnerable code path requires that the connection be closed on initialization of the SSLSocket.)