CVE-2026-50243

What it is

In NLnet Labs Unbound 1.6.2 up to and including 1.25.1, when Unbound is configured with the 'respip' module in front of the validator together with a 'response-ip' redirect rule or an RPZ file with an RPZ-IP trigger, the rewriting handler does not check the security status of the upstream answer and can instead rewrite a BOGUS A/AAAA answer to point to an operator's configured IP. If the validator finds an expired or otherwise invalid RRSIG on an answer whose A record falls within a 'response-ip'/RPZ configuration, the answer is still rewritten and given a hard coded security level of INSECURE. This results in the client receiving an INSECURE NOERROR reply rewritten by the operator's configured IP. A malicious actor can exploit the possible poisonous effect by spoofing a BOGUS A/AAAA answer that falls inside the operator's configured subnet rewrites. Such DNSSEC protected answers are then insecurely redirected to the operator's configured target.

At a glance

Exploitability

Can be exploited over the network without logging in. Limited direct impact.

Exploit odds

0.1% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-07-22 14:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-24 13:10 UTC Last updatedMost recent change to the record

Details

Published

2026-07-22 14:17 UTC

Last modified

2026-10-24 13:10 UTC

Exploit probability

0.1% · EPSS, next 30 days

Weakness

CWE-348

Record status

Analyzed

Affected

• Nlnetlabs Unbound < 1.25.2

Attack profile CVSS 4.0 · 6.3

Attack vector

Network

Complexity

High

Attack requirements

None

Privileges needed

None

User interaction

None

Confidentiality

None

Integrity

Low

Availability

None