// For flags

CVE-2023-40217

python: TLS handshake bypass

Severity Score

5.3
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

Attend
*SSVC
Descriptions

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.)

Python ssl.SSLSocket is vulnerable to a bypass of the TLS handshake in certain instances for HTTPS servers and other server-side protocols that use TLS client authentication such as mTLS. This issue may result in a breach of integrity as its possible to modify or delete resources that are authenticated only by a TLS certificate. No breach of confidentiality is possible.

*Credits: N/A
CVSS Scores
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
None
Integrity
High
Availability
None
* Common Vulnerability Scoring System
SSVC
  • Decision:Attend
Exploitation
None
Automatable
Yes
Tech. Impact
Partial
* Organization's Worst-case Scenario
Timeline
  • 2023-08-10 CVE Reserved
  • 2023-08-25 CVE Published
  • 2024-09-26 EPSS Updated
  • 2024-10-02 CVE Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-305: Authentication Bypass by Primary Weakness
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Python
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Python
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< 3.8.18
Search vendor "Python" for product "Python" and version " < 3.8.18"
-
Affected
Python
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Python
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>= 3.9.0 < 3.9.18
Search vendor "Python" for product "Python" and version " >= 3.9.0 < 3.9.18"
-
Affected
Python
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Python
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>= 3.10.0 < 3.10.13
Search vendor "Python" for product "Python" and version " >= 3.10.0 < 3.10.13"
-
Affected
Python
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Python
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>= 3.11.0 < 3.11.5
Search vendor "Python" for product "Python" and version " >= 3.11.0 < 3.11.5"
-
Affected