CVE-2026-50243
Description
A flaw in Unbound's respip module fails to verify the security status of incoming DNS answers when using response-ip rules or RPZ files. A remote attacker can exploit this by spoofing DNS answers to bypass DNSSEC protections and trigger unauthorized rewrites, redirecting clients to unintended locations.
Statement
This vulnerability has a Low impact because it requires Unbound to be specifically configured with the 'respip' module and either a 'response-ip' redirect rule or an RPZ file. This non-default setup allows a remote attacker to spoof DNS answers, resulting in the insecure redirection of DNSSEC protected responses.
Mitigation
If IP-based rewriting is unused, leave module-config configured as "validator iterator" and do not configure response-ip redirects or RPZ-IP triggers. If these features are required, ensure validator is placed before respip in module-config and restrict upstream peer access to reduce exposure to spoofed DNS answers.
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 | 3.7 | 3.7 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | High | High | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | Low | Low | N/A |
| Availability Impact | None | None | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
NVD: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Understanding the Weakness (CWE)
Access Control
Technical Impact: Bypass Protection Mechanism; Gain Privileges or Assume Identity
An attacker could utilize the untrusted data source to bypass protection mechanisms and gain access to sensitive data.
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