CVE-2026-50243

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.

CVSS v3 3.7 LOW

3.7^/10

CVSS v3 : LOW

Vector :

Exploitability : 2.2 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity HIGH

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact LOW

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-50243.txt	Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:nlnetlabs:unbound:*:*:*:*:*:*:*:*

History

24 Jul 2026, 13:59

Type	Values Removed	Values Added
CPE		cpe:2.3:a:nlnetlabs:unbound::::::::
References	~~() https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-50243.txt -~~	() https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-50243.txt - Vendor Advisory
First Time		Nlnetlabs Nlnetlabs unbound
CVSS	v2 : ~~unknown~~ v3 : ~~unknown~~	v2 : unknown v3 : 3.7

22 Jul 2026, 14:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-07-22 14:17

Updated : 2026-07-24 13:59

NVD link : CVE-2026-50243

Mitre link : CVE-2026-50243

CVE.ORG link : CVE-2026-50243

JSON object : View

Products Affected

nlnetlabs

unbound

CWE

CWE-348

Use of Less Trusted Source

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