CVE-2026-116566
Description
A flaw was found in Python. An attacker could bypass security controls and redirect network connections to unintended destinations due to improper input handling in the socket.getaddrinfo() function. Specifically, when host or port parameters contain null byte characters, the values are silently truncated during address resolution. This flaw enables attackers who supply network inputs to evade validation filters, such as domain or port allowlists.
Statement
Red Hat has evaluated this vulnerability as Moderate because exploitation is limited to applications that forward unsanitized external input to hostname resolution routines while relying on prefix-based or suffix-based validation. While an attacker can cause target destinations to be interpreted differently by the resolver compared to preceding security checks, this does not directly compromise system integrity or allow arbitrary remote code execution. Standard system utilities and hardened network services that perform strict input verification or resolve predefined endpoints remain unaffected.
Mitigation
Reject or sanitize null bytes in host and port values before calling socket.getaddrinfo(), or upgrade to CPython 3.16.0+ or a build carrying the backported fix (upstream PRs #160925/#160926/#160974/#160975/#160977 for 3.15/3.14/3.13/3.12/3.11).
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.3 | N/A | N/A |
| Attack Vector | Network | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | None | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | Low | N/A | N/A |
| Availability Impact | None | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Understanding the Weakness (CWE)
Integrity
Technical Impact: Unexpected State
Frequently Asked Questions
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