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National Vulnerability Database

National Vulnerability Database

NVD

National Vulnerability Database
  1. Vulnerabilities

CVE-2025-5994 Detail

Description

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.


Metrics

 
NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.
CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

Nist CVSS score does not match with CNA score
CNA:  NLnet Labs
CVSS-B 8.7 HIGH
Vector:  CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/R:U/V:C

References to Advisories, Solutions, and Tools

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URL Source(s) Tag(s)
https://nlnetlabs.nl/downloads/unbound/CVE-2025-5994.txt NLnet Labs

Weakness Enumeration

CWE-ID CWE Name Source
CWE-349 Acceptance of Extraneous Untrusted Data With Trusted Data NLnet Labs  

Change History

1 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2025-5994
NVD Published Date:
07/16/2025
NVD Last Modified:
07/17/2025
Source:
NLnet Labs