Buffer overread when using an empty list with SSLContext.set_npn_protocols()

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2024-5642
StatePUBLISHED
AssignerPSF
Source PriorityCVE Program / NVD first with legacy fallback
Published2024-06-27 21:15:16 UTC
Updated2026-07-31 15:16:26 UTC
DescriptionCPython 3.9 and earlier doesn't disallow configuring an empty list ("[]") for SSLContext.set_npn_protocols() which is an invalid value for the underlying OpenSSL API. This results in a buffer over-read when NPN is used (see CVE-2024-5535 for OpenSSL). This vulnerability is of low severity due to NPN being not widely used and specifying an empty list likely being uncommon in-practice (typically a protocol name would be configured).

Risk And Classification

Primary CVSS: v3.1 6.5 MEDIUM from ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L

EPSS: 0.007440000 probability, percentile 0.511920000 (date 2026-08-03)

Problem Types: CWE-noinfo Not enough information

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Python Software Foundation CPython affected 3.9.24 python Not specified
CNA Python Software Foundation CPython affected 3.10.0a1 3.10.0b1 python Not specified

References

ReferenceSourceLinkTags
mail.python.org/archives/list/[email protected]/thread/PLP2JI3PJY3... af854a3a-2127-422b-91ae-364da2661108 mail.python.org
jbp.io/2024/06/27/cve-2024-5535-openssl-memory-safety.html af854a3a-2127-422b-91ae-364da2661108 jbp.io
github.com/python/cpython/pull/23014 af854a3a-2127-422b-91ae-364da2661108 github.com
github.com/python/cpython/issues/121227 af854a3a-2127-422b-91ae-364da2661108 github.com
security.netapp.com/advisory/ntap-20240726-0005 af854a3a-2127-422b-91ae-364da2661108 security.netapp.com
www.openwall.com/lists/oss-security/2024/06/28/4 af854a3a-2127-422b-91ae-364da2661108 www.openwall.com
github.com/python/cpython/commit/39258d3595300bc7b952854c915f63ae2d4b9c3e af854a3a-2127-422b-91ae-364da2661108 github.com
github.com/python/cpython/commit/a2cdbb6e8188ba9ba8b356b28d91bff60e86fe31 [email protected] github.com
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