# 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.

- Web page: https://patchblox.com/security/cve/CVE-2026-116566
- Priority: Routine
- CVSS: 5.3 (Moderate)
- EPSS: 0.0026
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 29, 2026
- Weakness: Improper Neutralization of Null Byte or NUL Character
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-116566

## Description

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

## Where it's fixed

No fix is on record.

## No fix yet

| Platform | Product | Status |
|---|---|---|
| Windows apps | Python 2 | no-fix |
| Windows apps | Python 3.10 | no-fix |
| Windows apps | Python 3.11 | no-fix |
| Windows apps | Python 3.12 | no-fix |
| Windows apps | Python 3.13 | no-fix |
| Windows apps | Python 3.14 | no-fix |
| Windows apps | Python 3.5 | no-fix |
| Windows apps | Python 3.6 | no-fix |
| Windows apps | Python 3.7 | no-fix |
| Windows apps | Python 3.8 | no-fix |
| Windows apps | Python 3.9 | no-fix |
| macOS | Python3 | no-fix |

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Data as of 2026-11-10T01:44:33Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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