CVE-2025-5994

July 17, 2025, 9:15 p.m.

8.7
High

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.

Product(s) Impacted

Vendor Product Versions
Nlnetlabs
  • Unbound
  • *

Weaknesses

Common security weaknesses mapped to this vulnerability.

CWE-349
Acceptance of Extraneous Untrusted Data With Trusted Data
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.

*CPE(s)

Affected systems and software identified for this CVE.

Type Vendor Product Version Update Edition Language Software Edition Target Software Target Hardware Other Information
a nlnetlabs unbound / / / / / / / /

References

https://nlnetlabs.nl/downloads/unbound/CVE-2025-5994.txt

Tags

CWE-349
sep@nlnetlabs.nl
2025-07-16
CVE-2025-5994

CVSS Score

8.7 / 10

CVSS Data - 4.0

  • Attack Vector: NETWORK
  • Attack Complexity: LOW
  • Attack Requirements: NONE
  • Privileges Required: NONE
  • User Interaction: NONE
  • Scope:
  • Confidentiality Impact: NONE
  • Integrity Impact: HIGH
  • Availability Impact: NONE
  • Exploit Maturity: NOT_DEFINED

    • 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:U/V:C/RE:X/U:X

    View Vector String

Timeline

Published: July 16, 2025, 3:15 p.m.
Last Modified: July 17, 2025, 9:15 p.m.

Status : Awaiting Analysis

CVE has been recently published to the CVE List and has been received by the NVD.

More info

Source

sep@nlnetlabs.nl

*Disclaimer: Some vulnerabilities do not have an associated CPE. To enhance the data, we use AI to infer CPEs based on CVE details. This is an automated process and might not always be accurate.