NLnet Labs Unbound up to 1.25.1

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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6.2$0-$5k0.00

Summaryinfo

A vulnerability identified as critical has been detected in NLnet Labs Unbound up to 1.25.1. Impacted is an unknown function. This manipulation causes an unknown weakness. This vulnerability is handled as CVE-2026-42955. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability classified as critical was found in NLnet Labs Unbound up to 1.25.1. As an impact it is known to affect integrity, and availability. The summary by CVE is:

In NLnet Labs Unbound 1.16.2 up to and including 1.25.1, a similar vulnerability as with CVE-2026-40622 in the 'ghost domain names' family of attacks was found in Unbound that could extend the ghost domain window by up to one cached TTL configured value for A/AAAA glue records. Similar to other 'ghost domain names' attacks, an adversary needs to control a (ghost) zone and be able to query a vulnerable Unbound. A single client A/AAAA query can cause Unbound to overwrite the cached expired parent-side glue rrset and essentially extend the ghost domain window by up to one cached TTL configured value ('cache-max-ttl'). In configurations where 'harden-referral-path: yes' is used (non-default configuration), no client query is required since Unbound implicitly performs that query. This is a variant of CVE-2026-40622 which only addressed the NS query.

The advisory is shared at nlnetlabs.nl. This vulnerability is known as CVE-2026-42955 since 06/22/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Neither technical details nor an exploit are publicly available.

Upgrading to version 1.25.2 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-2492). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

  • Open Source Unbound

Productinfo

Vendor

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.5
VulDB Meta Temp Score: 6.2

VulDB Base Score: 6.5
VulDB Temp Score: 6.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Unknown
CWE: Unknown
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Unbound 1.25.2

Timelineinfo

06/22/2026 CVE reserved
07/22/2026 +30 days Advisory disclosed
07/22/2026 +0 days VulDB entry created
07/23/2026 +1 days VulDB entry last update

Sourcesinfo

Advisory: nlnetlabs.nl
Status: Confirmed

CVE: CVE-2026-42955 (🔒)
GCVE (CVE): GCVE-0-2026-42955
GCVE (VulDB): GCVE-100-382321
CERT Bund: WID-SEC-2026-2492 - Unbound: Mehrere Schwachstellen

Entryinfo

Created: 07/22/2026 15:43
Updated: 07/23/2026 17:31
Changes: 07/22/2026 15:43 (51), 07/23/2026 17:31 (8)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Discussion

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