NLnet Labs Unbound up to 1.22.x DNS Transaction ID acceptance of extraneous untrusted data with trusted data

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5.1$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as problematic, was found in NLnet Labs Unbound up to 1.22.x. Impacted is an unknown function of the component DNS Transaction ID Handler. Such manipulation leads to acceptance of extraneous untrusted data with trusted data. This vulnerability is referenced as CVE-2025-5994. It is possible to launch the attack remotely. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in NLnet Labs Unbound up to 1.22.x. Affected by this issue is some unknown functionality of the component DNS Transaction ID Handler. The manipulation with an unknown input leads to a acceptance of extraneous untrusted data with trusted data vulnerability. Using CWE to declare the problem leads to CWE-349. The product, when processing trusted data, accepts any untrusted data that is also included with the trusted data, treating the untrusted data as if it were trusted. Impacted is integrity. CVE summarizes:

A multi-vendor cache poisoning vulnerability named 'Rebirthday Attack' has been discovered in caching resolvers that support EDNS Client Subnet (ECS). Unbound is also vulnerable when compiled with ECS support, i.e., '--enable-subnet', AND configured to send ECS information along with queries to upstream name servers, i.e., at least one of the 'send-client-subnet', 'client-subnet-zone' or 'client-subnet-always-forward' options is used. Resolvers supporting ECS need to segregate outgoing queries to accommodate for different outgoing ECS information. This re-opens up resolvers to a birthday paradox attack (Rebirthday Attack) that tries to match the DNS transaction ID in order to cache non-ECS poisonous replies.

The weakness was published by Xiang Li. The advisory is shared for download at nlnetlabs.nl. This vulnerability is handled as CVE-2025-5994 since 06/11/2025. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are neither technical details nor an exploit publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 242937 (AlmaLinux 8 : unbound (ALSA-2025:11884)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 1.23.0 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (242937), EUVD (EUVD-2025-21730) and CERT Bund (WID-SEC-2025-2043). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

  • IBM QRadar SIEM

Productinfo

Vendor

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 5.3
VulDB Meta Temp Score: 5.1

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

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

Exploitinginfo

Class: Acceptance of extraneous untrusted data with trusted data
CWE: CWE-349
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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Nessus ID: 242937
Nessus Name: AlmaLinux 8 : unbound (ALSA-2025:11884)

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Unbound 1.23.0

Timelineinfo

06/11/2025 CVE reserved
07/16/2025 +35 days Advisory disclosed
07/16/2025 +0 days VulDB entry created
09/12/2025 +58 days VulDB entry last update

Sourcesinfo

Advisory: nlnetlabs.nl
Researcher: Xiang Li
Status: Confirmed

CVE: CVE-2025-5994 (🔒)
GCVE (CVE): GCVE-0-2025-5994
GCVE (VulDB): GCVE-100-316640
EUVD: 🔒
CERT Bund: WID-SEC-2025-2043 - IBM QRadar SIEM: Mehrere Schwachstellen

Entryinfo

Created: 07/16/2025 17:06
Updated: 09/12/2025 14:14
Changes: 07/16/2025 17:06 (69), 07/16/2025 19:21 (1), 07/29/2025 06:24 (2), 09/12/2025 14:14 (7)
Complete: 🔍
Cache ID: 216::103

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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