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CVE-2026-50243

INDEX BUILT · 2026-09-20

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'response-ip'/'rpz' can rewrite BOGUS answers instead of returning SERVFAIL

CVE-2026-502434 of 4 sources documented this
11

rank 11 = 0 + 9 + 0 + 2 + 0

rank@v1 · backlog

Someone is already using it

CISA KEV catalog · public proof-of-concept · FIRST EPSS

EPSS 0.00103  ·  without this subject the record ranks 11

What it costs you if it fires

NVD CVSS base score, then the CNA's own

CVSS 3.7, from NVD  ·  without this subject the record ranks 2

It is getting worse, not staying still

FIRST EPSS series, rescorings and bad loads removed

no persisting rise in 365 days  ·  without this subject the record ranks 11

How much of the world it touches

NVD CPE configurations

1 product in the CPE ranges  ·  without this subject the record ranks 9

Someone else already set the date

CISA KEV remediation due date

no CISA due date  ·  without this subject the record ranks 11

Unaudited dollar value2 of 3 inputs carry a receipt
Exposure$1,240over the next 30 days, if this record is yours
Movementno material movementthe record holds only daily drift and scoring model releases
Basisassumeda published average, not your estate

$1,240 = $4.99M incident cost x 0.24048551839932833 exposure x 0.00103 likelihood

udv@v1 · unaudited · wrong for you until you say what you run

$4.99M is the cost of a breach that happened, from IBM Cost of a Data Breach Report 2026, global average. It is not the value of any asset of yours. That average already covers breaches of every severity, so scaling it by exposure understates a partial-impact record. That is an assumption, not a measurement. Your own asset value goes in the decision record.

Hindsight · the state

0.00103EPSSNOT IN KEVas of 2026-09-20
Severity6.3 MEDIUMreceipt
Harmunauthenticated · networkreceipt
Exploitationnone in held sources
Defensefix version namedreceipt
Movementfallenreceipt
PLATEAU10Minimal movement since 2026-07-23, 36 days at 0.00, as of 2026-08-28. arc-rules@v1

Foresight · where to check next

No weakness class or product neighbourhood is held for this record, so this index cannot name anywhere to check next. That is an absence in the record, not a finding about the software.

Color is a claim, not decoration:the hostile worldthe defenseno signal

Sources disagree here.

Severity score
NLnet Labs6.3 MEDIUMreceipt
NVD3.7 LOWreceipt
Scoring standard
NLnet LabsCVSS v4.0receipt
NVDCVSS v3.1receipt

Both shown, dated. We don't pick winners. disagreement-rules@v1

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Harm, if it fires from the vector and the weakness

Written for the ticket you're about to file.

Reachnetwork-reachable · no privileges required · no user interaction · high attack complexity · no attack requirementsreceipt
ImpactPartial integrity loss, with impact on subsequent systemsreceipt
Scored fromCVSS v4.0 · the CNA's vectorreceipt
Weakness classCWE-348 Use of Less Trusted Sourcereceipt
Published consequencesCWE-348: Access Control: Bypass Protection Mechanism, Gain Privileges or Assume Identity[email protected]

CISA KEV & Federal Remediation Deadline from the record and CISA

The fix, and how long it's been waiting.

Fixed in1.25.2receipt
Patch available sinceNo dated patch-availability record in held sources. The index holds reference URLs without dates and only the current revision of the CVE record, so the day a fix first existed cannot be derived. Only the versions it landed in.

Exploit Status & Known PoCs a ladder, not a score

Current rung: Nothing observed in held sources.

  • RUNG 1Nothing observed in held sources
  • RUNG 2Proof-of-concept published
  • RUNG 3Exploited in the wild · CISA KEV listed
  • RUNG 4Ransomware campaign use known

Authority who says so

CVSS, the CNA6.3 MEDIUMreceipt
CVSS, NVD3.7 LOWreceipt
Exploit probability0.00103 · top 99% of all CVEsreceipt
Blast breadth1 product across 1 vendorderived
Assigned byNLnet Labsreceipt
Recorded changes4 · last 19 Sep 2026derived

Affected & Fixed Versions as published

Affected productNLnet Labs Unboundreceipt
Published rangesnlnetlabs unbound >= 1.6.2 < 1.25.2receipt
Fixed in1.25.2receipt

A rung lights from a row in the index, never from an assessment. "Held sources" is the true scope of the claim: this index reads the CVE record, NVD, CISA KEV, FIRST's EPSS and public proof-of-concept repositories, and it does not observe attacks.

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What it is stated by the CNA

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. receipt

Read the rest of the CNA's description

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.

NVD's analysis a second authority

severity
3.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
weakness
CWE-348
affected versions
nlnetlabs unbound >= 1.6.2 < 1.25.2
also scored by
[email protected] 6.3 CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

The CNA scored it 6.3 and NVD 3.7. Both are shown because both were published; we do not pick one.

check it yourself nlnetlabs.nl receipt

Movement the material steps

23 Jul 20260.00169
28 Aug 20260.00103
Show all 4 observations
23 Jul 20260.00169
24 Jul 20260.0013
25 Jul 20260.00107
28 Aug 20260.00103

4 observations held. A highlighted step crossed a promotion threshold. A step marked with a scoring model moved because the instrument was replaced, not because the vulnerability changed. receipt

The full biography

EPSS 0.00103Published2026-07-22Index as of2026-08-28

The record had been public for 1 month when this index was last written.

Published 2026-07-22 receipt · Index as of 2026-08-28 derived

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