CVE-2023-40217

Advisory lineage Upstream: 0 Downstream: 54
Modified
Published: 25 Aug 2023, 00:00
Last modified:03 Nov 2025, 21:49

Vulnerability Summary

Overall Risk (default)
low
21/100
CVSS Score
5.3 MEDIUM
v3.1 (nvd)
EPSS Score
0.58% LOW
1% probability 0.00%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

25 Aug 2023, 00:00
Published
Vulnerability first disclosed
03 Nov 2025, 21:49
Last Modified
Vulnerability information updated

Description

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.)

CVSS Metrics

  • v3.1•MEDIUM•Score: 5.3CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS Trends

Current EPSS score: 0.58%• Percentile: 69%

Affected Systems

  • python•python

    < 3.8.18 | ≥ 3.9.0, < 3.9.18 | ≥ 3.10.0, < 3.10.13 | ≥ 3.11.0, < 3.11.5

References (7)