F5-K000159546: Low severity F5 F5OS-A vulnerability

Published Jan 14, 2026
·
Updated

CPython 3.9 and earlier doesn't disallow configuring an empty list ("[]") for SSLContext.setnpnprotocols() 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 Software

2 affected components
F5 F5OS-A>=1.8.0<=1.8.3, >=1.5.1<=1.5.4
F5 F5OS-C>=1.8.0<=1.8.2, >=1.6.0<=1.6.4

Event History

Jan 14, 2026
Advisory Published
via F5·04:03 PM
Data Sourced
via F5·04:03 PM
DescriptionSeverityWeaknessAffected Software
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Frequently Asked Questions

1

What is the severity of F5-K000159546?

The severity of F5-K000159546 is considered low.

2

How do I fix F5-K000159546?

To fix F5-K000159546, ensure that valid protocols are configured for SSLContext.set_npn_protocols() instead of an empty list.

3

Which products are affected by F5-K000159546?

F5-K000159546 affects F5OS-A versions from 1.5.1 to 1.8.3 and F5OS-C versions from 1.6.0 to 1.8.2.

4

What is the nature of the vulnerability in F5-K000159546?

F5-K000159546 is a buffer over-read vulnerability resulting from configuring an invalid empty list for NPN protocols.

5

Is there a known CVE related to F5-K000159546?

Yes, F5-K000159546 is related to CVE-2024-5535, which pertains to the underlying OpenSSL API.

Contact

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