CVE-2026-80213
Description
A flaw was found in the resolv gem. This vulnerability arises from the incorrect handling of DNS label lengths during message encoding. A remote attacker could exploit this by providing a specially crafted hostname to an application utilizing the resolv gem. This could lead to the bypass of security controls such as allowlists and egress checks, as well as DNS cache poisoning, where a recursive resolver caches an attacker-chosen name instead of the intended one. This also results in inaccurate DNS logs.
Statement
This is a Moderate impact vulnerability in the Ruby resolv gem, which is part of the Ruby standard library. This flaw allows for DNS allowlist and egress bypass, and cache poisoning. When an application processes attacker-controlled hostnames, it can result in DNS queries for unintended domains, potentially circumventing network access restrictions or domain validation checks.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
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).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 4 | N/A | 4 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | High | N/A | High |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Changed | N/A | Changed |
| Confidentiality | None | N/A | None |
| Integrity Impact | Low | N/A | Low |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N
cve.org: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N
Understanding the Weakness (CWE)
Confidentiality,Integrity
Technical Impact: Read Memory; Modify Memory; Varies by Context
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
