Vulnerability · Published Jul 23, 2026 · Assigned by mitre
CVE-2026-39155
Medium 6.5
In plain English
A medium-severity insufficient verification of data authenticity in the knot package (Debian). There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 13% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Knot DNS before 3.4.10 and 3.5.x before 3.5.4 contains a vulnerability in mod-onlinesign where the next NSEC owner name can be computed incorrectly. This can create an overly broad authenticated denial interval, allowing downstream validating resolvers using aggressive negative caching to synthesize negative answers for legitimate names and causing resolver-side denial of service.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | knot | no fix listed | DEBIAN-CVE-2026-39155 |
| Debian:13 | knot | no fix listed | DEBIAN-CVE-2026-39155 |
| Debian:14 | knot | 3.5.4-1 | DEBIAN-CVE-2026-39155 |
| Ubuntu:22.04:LTS | knot | no fix listed | UBUNTU-CVE-2026-39155 |
| Ubuntu:24.04:LTS | knot | no fix listed | UBUNTU-CVE-2026-39155 |
| Ubuntu:26.04:LTS | knot | no fix listed | UBUNTU-CVE-2026-39155 |
Affected products (as reported)
Weakness: CWE-345 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H