NLnet Labs Unbound up to 1.25.1 Auth/Rpz Zone improper authentication

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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9.5$0-$5k2.02

Summaryinfo

A vulnerability was found in NLnet Labs Unbound up to 1.25.1. It has been classified as very critical. This issue affects some unknown processing of the component Auth/Rpz Zone. The manipulation leads to improper authentication. This vulnerability is documented as CVE-2026-50248. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability, which was classified as very critical, has been found in NLnet Labs Unbound up to 1.25.1. This issue affects an unknown code block of the component Auth/Rpz Zone. The manipulation with an unknown input leads to a improper authentication vulnerability. Using CWE to declare the problem leads to CWE-287. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

In NLnet Labs Unbound 1.7.0 up to and including 1.25.1, when an auth/rpz zone has a configured primary hostname that resolves to BOGUS A/AAAA, it is still considered as a possible XFR endpoint. A malicious actor that can spoof the hostname's A/AAAA record (no valid RRSIG required) becomes the zone's XFR primary and can replaces the entire zone/the resolver's entire response policy.

It is possible to read the advisory at nlnetlabs.nl. The identification of this vulnerability is CVE-2026-50248 since 06/22/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/22/2026).

Upgrading to version 1.25.2 eliminates this vulnerability.

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Vendor

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 10.0
VulDB Meta Temp Score: 9.5

VulDB Base Score: 10.0
VulDB Temp Score: 9.5
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: Improper authentication
CWE: CWE-287
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: no mitigation known
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
07/22/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: nlnetlabs.nl
Status: Confirmed

CVE: CVE-2026-50248 (🔒)
GCVE (CVE): GCVE-0-2026-50248
GCVE (VulDB): GCVE-100-382331

Entryinfo

Created: 07/22/2026 16:01
Changes: 07/22/2026 16:01 (53)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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