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🛡️ CVE-2026-50243 — unbound

🟢 CVSS 3.7 — Low ✅ No Known Exploit CWE-348 NVD
3.7
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

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.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is high, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity low, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: High — the attacker first has to win a race, learn a secret or otherwise prepare the target.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: None.
  • Integrity impact: Low — limited, and the attacker does not choose what is affected.
  • Availability impact: None.

Weakness class

CVE-2026-50243 is classified as CWE-348: Use of Less Trusted Source. The product has two different sources of the same data or information, but it uses the source that has less support for verification, is less trusted, or is less resistant to attack.

Affected software

CVE-2026-50243 is recorded against 1 package.

  • unbound (from 1.6.2 up to 1.25.2)

Timeline and source

Published on 22 July 2026 and last revised on 24 July 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

www.nlnetlabs.nl

Other advisories for this package

unbound has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-348: Use of Less Trusted Source) in other software:

Details

Severity LOW
CVSS Score 3.7
CVSS Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
CWE CWE-348
Public Exploit ✅ No
Source NVD
Published 2026-07-22
Updated 2026-08-20
Modified 2026-07-24
Fix URL N/A

Affected Packages

Software From version Fixed in
unbound 1.6.2 1.25.2

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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