CVE-2026-42955Network attack vector

Ghost-domain delegation renewal via expired glue overwrite

Published Jul 22, 2026 · Updated Jul 22, 2026

Cache poisoning in NLnet Labs Unbound 1.16.2 through 1.25.1 allows remote attackers to extend a ghost-domain delegation via DNS queries. The resolver lets an A or AAAA client query overwrite an expired parent-side glue RRset in cache, renewing its lifetime for as long as cache-max-ttl. Attackers must control the ghost zone and query the resolver; with non-default harden-referral-path enabled, Unbound issues the triggering query itself.

CVSS severity3.7
Low
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cache poisoning in NLnet Labs Unbound 1.16.2 through 1.25.1 allows remote attackers to extend a ghost-domain delegation via DNS queries. The resolver lets an A or AAAA client query overwrite an expired parent-side glue RRset in cache, renewing its lifetime for as long as cache-max-ttl. Attackers must control the ghost zone and query the resolver; with non-default harden-referral-path enabled, Unbound issues the triggering query itself.

The record

CVE
CVE-2026-42955
Published
Jul 22, 2026
Updated
Jul 22, 2026
Vendor
NLnet Labs
Product
Unbound
Classifications
CWE-672
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 22, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 22, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.16.2 <1.25.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

NLnet Labs · Unboundversion=1.16.2 <1.25.2

Published CVSS scores

3.7NLnet LabsCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-672Operation on a Resource after Expiration or Release

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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