CVE-2022-30699: NLnet Labs Unbound, up to and including version 1.16.1, is vulnerable to a novel type of the "ghost domain names" attack. The vulnerability works by t...

Description

NLnet Labs Unbound, up to and including version 1.16.1, is vulnerable to a novel type of the "ghost domain names" attack. The vulnerability works by targeting an Unbound instance. Unbound is queried for a rogue domain name when the cached delegation information is about to expire. The rogue nameserver delays the response so that the cached delegation information is expired. Upon receiving the delayed answer containing the delegation information, Unbound overwrites the now expired entries. This action can be repeated when the delegation information is about to expire making the rogue delegation information ever-updating. From version 1.16.2 on, Unbound stores the start time for a query and uses that to decide if the cached delegation information can be overwritten.

Metrics

CVSS 3.1

6.5/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

EPSS Probability

0.85%

53.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-613

Affected Software

Vendor	Product	Versions
Nlnetlabs	Unbound	< 1.16.2
Fedoraproject	Fedora	35
Fedoraproject	Fedora	36

References

Timeline

Published: Aug 1, 2022
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2022-30699?

NLnet Labs Unbound, up to and including version 1.16.1, is vulnerable to a novel type of the "ghost domain names" attack. The vulnerability works by targeting an Unbound instance. Unbound is queried for a rogue domain name when the cached delegation information is about to expire. The rogue nameserver delays the response so that the cached delegation information is expired. Upon receiving the delayed answer containing the delegation information, Unbound overwrites the now expired entries. This action can be repeated when the delegation information is about to expire making the rogue delegation information ever-updating. From version 1.16.2 on, Unbound stores the start time for a query and uses that to decide if the cached delegation information can be overwritten.

How severe is CVE-2022-30699?

CVE-2022-30699 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.85% probability of exploitation in the next 30 days.

How do I fix CVE-2022-30699?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.