PSF-2023-8

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Import Source
https://github.com/psf/advisory-database/blob/main/advisories/python/PSF-2023-8.json
JSON Data
https://api.osv.dev/v1/vulns/PSF-2023-8
Aliases
Published
2023-08-24T00:00:00Z
Modified
2023-12-06T00:48:09.043845Z
Summary
Bypass TLS handshake on closed sockets
Details

Instances of ssl.SSLSocket are vulnerable to a bypass of the TLS handshake and included protections (like certificate verification) and treating sent unencrypted data as if it were post-handshake TLS encrypted data.

The vulnerability is caused when a socket is connected, data is sent by the malicious peer and stored in a buffer, and then the malicious peer closes the socket within a small timing window before the other peers’ TLS handshake can begin. After this sequence of events the closed socket will not immediately attempt a TLS handshake due to not being connected but will also allow the buffered data to be read as if a successful TLS handshake had occurred.

Affected usages

This vulnerability primarily affects HTTPS servers and other server-side protocols using TLS client authentication due to requiring reading data immediately after the handshake to be vulnerable. Operations which would fail on a closed socket (like sending data) immediately after the handshake are not affected by this vulnerability.

Because disconnecting the socket is a necessary step to trigger the vulnerability there is no risk of data exfiltration or data leakage directly from the malicious TLS connection, however the vulnerability does carry risk for modifying or deleting resources which are authenticated using only TLS client certificates.

This vulnerability affects clients who are reading and processing data from the server after a TLS handshake without sending any data first. Our team is unaware of a protocol that uses TLS that fits this usage pattern.

This vulnerability does not affect client-side HTTPS connections like pip or requests as an HTTP request must be sent before an HTTP response is read meaning the connection would already be closed by the time the client is sending an HTTP request, leading to an error.

This vulnerability affects, but has no impact on servers that aren’t using TLS client certificate authentication as traffic to a non-authenticating TLS server loses nothing from a bypassed handshake to inject a query and close the connection as the same action could be taken by a peer using a TLS connection with a proper handshake.

References
Credits
    • Aapo Oksman - FINDER
    • Gregory P. Smith - REMEDIATION_DEVELOPER
    • Thomas Wouters - REMEDIATION_REVIEWER
    • Seth Michael Larson - COORDINATOR

Affected packages

Git / github.com/python/cpython

Affected ranges

Type
GIT
Repo
https://github.com/python/cpython
Events

Affected versions

2.*

2.5

3.*

3.2

v0.*

v0.9.8
v0.9.9

v1.*

v1.0.1
v1.0.2
v1.1
v1.1.1
v1.2
v1.2b1
v1.2b2
v1.2b3
v1.2b4
v1.3
v1.3b1
v1.4
v1.4b1
v1.4b2
v1.4b3
v1.5
v1.5.1
v1.5.2
v1.5.2a1
v1.5.2a2
v1.5.2b1
v1.5.2b2
v1.5.2c1
v1.5a1
v1.5a2
v1.5a3
v1.5a4
v1.5b1
v1.5b2
v1.6a1
v1.6a2

v2.*

v2.0
v2.0b1
v2.0b2
v2.0c1
v2.1
v2.1a1
v2.1a2
v2.1b1
v2.1b2
v2.1c1
v2.1c2
v2.2a3
v2.3c1
v2.3c2
v2.4
v2.4a1
v2.4a2
v2.4a3
v2.4b1
v2.4b2
v2.4c1
v2.5
v2.5.1
v2.5.1c1
v2.5.2
v2.5.2c1
v2.5.3
v2.5.3c1
v2.5.4
v2.5.5
v2.5.5c1
v2.5.5c2
v2.5.6
v2.5.6c1
v2.5a0
v2.5a1
v2.5a2
v2.5b1
v2.5b2
v2.5b3
v2.5c1
v2.5c2
v2.6
v2.6.1
v2.6.2
v2.6.2c1
v2.6.3
v2.6.3rc1
v2.6.4
v2.6.4rc1
v2.6.4rc2
v2.6.5
v2.6.5rc1
v2.6.5rc2
v2.6.6
v2.6.6rc1
v2.6.6rc2
v2.6.7
v2.6.8
v2.6.8rc1
v2.6.8rc2
v2.6a1
v2.6a2
v2.6a3
v2.6b1
v2.6b2
v2.6b3
v2.6rc1
v2.6rc2
v2.7
v2.7.1
v2.7.1rc1
v2.7.2
v2.7.2rc1
v2.7.3
v2.7.3rc1
v2.7.3rc2
v2.7.4rc1
v2.7a1
v2.7a2
v2.7a3
v2.7a4
v2.7b1
v2.7b2
v2.7rc1
v2.7rc2

v3.*

v3.0a1
v3.0a2
v3.0a3
v3.0a4
v3.0a5
v3.0b1
v3.0b2
v3.0b3
v3.0rc1
v3.0rc2
v3.0rc3
v3.1
v3.1.1
v3.1.1rc1
v3.1.2
v3.1.2rc1
v3.1.3
v3.1.3rc1
v3.1.4
v3.1.4rc1
v3.1.5
v3.1.5rc1
v3.1.5rc2
v3.10.0
v3.10.0a1
v3.10.0a2
v3.10.0a3
v3.10.0a4
v3.10.0a5
v3.10.0a6
v3.10.0a7
v3.10.0b1
v3.10.0b2
v3.10.0b3
v3.10.0b4
v3.10.0rc1
v3.10.0rc2
v3.10.1
v3.10.10
v3.10.11
v3.10.12
v3.10.2
v3.10.3
v3.10.4
v3.10.5
v3.10.6
v3.10.7
v3.10.8
v3.10.9
v3.11.0
v3.11.0a1
v3.11.0a2
v3.11.0a3
v3.11.0a4
v3.11.0a5
v3.11.0a6
v3.11.0a7
v3.11.0b1
v3.11.0b2
v3.11.0b3
v3.11.0b4
v3.11.0b5
v3.11.0rc1
v3.11.0rc2
v3.11.1
v3.11.2
v3.11.3
v3.11.4
v3.12.0a1
v3.12.0a2
v3.12.0a3
v3.12.0a4
v3.12.0a5
v3.12.0a6
v3.12.0a7
v3.12.0b1
v3.12.0b2
v3.12.0b3
v3.12.0b4
v3.12.0rc1
v3.1a1
v3.1a2
v3.1b1
v3.1rc1
v3.1rc2
v3.2
v3.2.1
v3.2.1b1
v3.2.1rc1
v3.2.1rc2
v3.2.2
v3.2.2rc1
v3.2.3
v3.2.3rc1
v3.2.3rc2
v3.2.4
v3.2.4rc1
v3.2.5
v3.2.6
v3.2.6rc1
v3.2a1
v3.2a2
v3.2a3
v3.2a4
v3.2b1
v3.2b2
v3.2rc1
v3.2rc2
v3.2rc3
v3.3.0
v3.3.0a1
v3.3.0a2
v3.3.0a3
v3.3.0a4
v3.3.0b1
v3.3.0b2
v3.3.0rc1
v3.3.0rc2
v3.3.0rc3
v3.3.1
v3.3.1rc1
v3.3.2
v3.3.3
v3.3.3rc1
v3.3.3rc2
v3.3.4
v3.3.4rc1
v3.3.5
v3.3.5rc1
v3.3.5rc2
v3.3.6
v3.3.6rc1
v3.4.0
v3.4.0a1
v3.4.0a2
v3.4.0a3
v3.4.0a4
v3.4.0b1
v3.4.0b2
v3.4.0b3
v3.4.0rc1
v3.4.0rc2
v3.4.0rc3
v3.4.1
v3.4.1rc1
v3.4.2
v3.4.2rc1
v3.4.3
v3.4.3rc1
v3.4.4
v3.4.4rc1
v3.4.5
v3.4.5rc1
v3.4.6
v3.4.6rc1
v3.5.0
v3.5.0a1
v3.5.0a2
v3.5.0a3
v3.5.0a4
v3.5.0b1
v3.5.0b2
v3.5.0b3
v3.5.0b4
v3.5.0rc1
v3.5.0rc2
v3.5.0rc3
v3.5.0rc4
v3.5.1
v3.5.1rc1
v3.5.2
v3.5.2rc1
v3.5.3
v3.5.3rc1
v3.6.0
v3.6.0a1
v3.6.0a2
v3.6.0a3
v3.6.0a4
v3.6.0b1
v3.6.0b2
v3.6.0b3
v3.6.0b4
v3.6.0rc1
v3.6.0rc2
v3.7.0a1
v3.7.0a2
v3.7.0a3
v3.7.0a4
v3.8.0
v3.8.0a1
v3.8.0a2
v3.8.0a3
v3.8.0a4
v3.8.0b1
v3.8.0b2
v3.8.0b3
v3.8.0b4
v3.8.0rc1
v3.8.1
v3.8.10
v3.8.11
v3.8.12
v3.8.13
v3.8.14
v3.8.15
v3.8.16
v3.8.17
v3.8.1rc1
v3.8.2
v3.8.2rc1
v3.8.2rc2
v3.8.3
v3.8.3rc1
v3.8.4
v3.8.4rc1
v3.8.5
v3.8.6
v3.8.6rc1
v3.8.7
v3.8.7rc1
v3.8.8
v3.8.8rc1
v3.8.9
v3.9.0
v3.9.0a1
v3.9.0a2
v3.9.0a3
v3.9.0a4
v3.9.0a5
v3.9.0a6
v3.9.0b1
v3.9.0b2
v3.9.0b3
v3.9.0b4
v3.9.0b5
v3.9.0rc1
v3.9.0rc2
v3.9.1
v3.9.10
v3.9.11
v3.9.12
v3.9.13
v3.9.14
v3.9.15
v3.9.16
v3.9.17
v3.9.1rc1
v3.9.2
v3.9.2rc1
v3.9.3
v3.9.4
v3.9.5
v3.9.6
v3.9.7
v3.9.8
v3.9.9