Bug 2506132 (CVE-2026-50243) - CVE-2026-50243 unbound: Unbound: Insecure DNS redirection via spoofed DNS answers
Summary: CVE-2026-50243 unbound: Unbound: Insecure DNS redirection via spoofed DNS ans...
Keywords:
Status: NEW
Alias: CVE-2026-50243
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
low
low
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-07-22 14:01 UTC by OSIDB Bzimport
Modified: 2026-08-26 12:15 UTC (History)
17 users (show)

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Description OSIDB Bzimport 2026-07-22 14:01:34 UTC
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.


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