CVE-2026-116566

socket.getaddrinfo() accepts embedded null bytes in host and port

CVE-2026-116566 has no fix on record yet for 12 affected products. It is not reported as exploited. Patch Radar priority: Routine.

RoutineFixed on 2 platforms

CVSS

5.3

Moderate

Exploitation

None reported

No vendor assessment

CISA KEV

Not listed

Not in the Known Exploited Vulnerabilities catalog

EPSS

0.0026

17th percentile

socket.getaddrinfo() previously accepted null bytes within *host* and *port* parameters which can cause the values to be silently truncated.

Where it's fixed

Product	Fixed in	Fix	Released
No fix yet
Python 2 (Windows apps)	No fix yet	no-fix	n/a
Python 3.10 (Windows apps)	No fix yet	no-fix	n/a
Python 3.11 (Windows apps)	No fix yet	no-fix	n/a
Python 3.12 (Windows apps)	No fix yet	no-fix	n/a
Python 3.13 (Windows apps)	No fix yet	no-fix	n/a
Python 3.14 (Windows apps)	No fix yet	no-fix	n/a
Python 3.5 (Windows apps)	No fix yet	no-fix	n/a
Python 3.6 (Windows apps)	No fix yet	no-fix	n/a
Python 3.7 (Windows apps)	No fix yet	no-fix	n/a
Python 3.8 (Windows apps)	No fix yet	no-fix	n/a
Python 3.9 (Windows apps)	No fix yet	no-fix	n/a
Python3 (macOS)	No fix yet	no-fix	n/a

Details

Published
October 29, 2026
Weakness
Improper Neutralization of Null Byte or NUL Character
Vendor advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-116566

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