CVE-2024-5642: Buffer overread when using an empty list with SSLContext.set_npn_protocols()
First published: Thu Jun 27 2024(Updated: )
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).
Credit: cna@python.org
| Affected Software | Affected Version | How to fix |
|---|---|---|
| CPython | <3.9 | |
| OpenSSL libcrypto |
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Reference Links
- http://www.openwall.com/lists/oss-security/2024/06/28/4
- https://github.com/python/cpython/commit/39258d3595300bc7b952854c915f63ae2d4b9c3e
- https://github.com/python/cpython/issues/121227
- https://github.com/python/cpython/pull/23014
- https://jbp.io/2024/06/27/cve-2024-5535-openssl-memory-safety.html
- https://mail.python.org/archives/list/security-announce@python.org/thread/PLP2JI3PJY33YG6P5BZYSSNU66HASXBQ/
- https://security.netapp.com/advisory/ntap-20240726-0005/
Frequently Asked Questions
What is the severity of CVE-2024-5642?
The severity of CVE-2024-5642 is classified as low.
How do I fix CVE-2024-5642?
To fix CVE-2024-5642, ensure that your application does not configure an empty list for SSLContext.set_npn_protocols().
Which versions of CPython are affected by CVE-2024-5642?
CVE-2024-5642 affects CPython versions 3.9 and earlier.
What kind of issue does CVE-2024-5642 cause?
CVE-2024-5642 results in a buffer over-read when NPN is used due to an invalid value.
Is CVE-2024-5642 related to OpenSSL?
Yes, CVE-2024-5642 is related to OpenSSL, as it affects the underlying API used in conjunction with SSLContext.
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