CVE-2026-39155
Knot DNS mod-onlinesign Authenticated Denial of Service Vulnerability
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.
INFO
Published Date :
July 23, 2026, 9:17 p.m.
Last Modified :
July 23, 2026, 9:17 p.m.
Remotely Exploit :
No
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-39155
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
Solution
- Update Knot DNS to version 3.4.10 or later.
- Update Knot DNS to version 3.5.4 or later.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-39155.
| URL | Resource |
|---|---|
| https://www.knot-dns.cz/2026-04-01-version-3410.html | |
| https://www.knot-dns.cz/2026-04-02-version-354.html |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-39155 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-39155
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-39155 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-39155 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Jul. 23, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'n/a', 'product': 'n/a', 'versions': [{'status': 'affected', 'version': 'n/a'}]}] Added 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. Added Reference https://www.knot-dns.cz/2026-04-01-version-3410.html Added Reference https://www.knot-dns.cz/2026-04-02-version-354.html