Denial of service in Python NPN support

1) Out-of-bounds read

EUVDB-ID: #VU97633

Risk: Low

CVSSv3.1: 3.8 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L/E:U/RL:O/RC:C]

CVE-ID: CVE-2024-5642

CWE-ID: CWE-125 - Out-of-bounds read

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to 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 when NPN is used. A remote attacker can trigger an out-of-bounds read error and perform a denial of service (DoS) attack.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Python: 3.7 - 3.9.19

CPE2.3

• cpe:2.3:a:python_org:python:3.7.17:*:*:*:*:*:*:*
• cpe:2.3:a:python_org:python:3.8.19:*:*:*:*:*:*:*
• cpe:2.3:a:python_org:python:3.9.19:*:*:*:*:*:*:*

External links

http://jbp.io/2024/06/27/cve-2024-5535-openssl-memory-safety.html
http://github.com/python/cpython/pull/23014
http://mail.python.org/archives/list/security-announce@python.org/thread/PLP2JI3PJY33YG6P5BZYSSNU66HASXBQ/
http://github.com/python/cpython/commit/39258d3595300bc7b952854c915f63ae2d4b9c3e
http://www.openwall.com/lists/oss-security/2024/06/28/4
http://github.com/python/cpython/issues/121227
http://security.netapp.com/advisory/ntap-20240726-0005/
http://github.com/advisories/GHSA-hrvr-7x5w-xpmq

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.