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6.5 Medium

CVE-2024-5642 CPython 3.9 and earlier doesn't disallow configuring an empty list ("[]") for SSLContext.set_npn_protocols() which is an…

Description

CPython 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).

Affected products and versions

Product Affected versions Fixed in
CPython 3.10 3.10.0a1 → < 3.10.0b1 3.10.0b1
CPython 3.9 earliest → < 3.9.24 3.9.24

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