CVE-2019-10190: A vulnerability was discovered in DNS resolver component of knot resolver through version 3.2.0 before 4.1.0 w

This month

HIGH 7.5REMOTEUPGRADEMITIGATE

CVE-2019-10190 is a high-severity flaw (CVSS 7.5) affecting knot resolver, fedora. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A vulnerability was discovered in DNS resolver component of knot resolver through version 3.2.0 before 4.1.0 which allows remote attackers to bypass DNSSEC validation for non-existence answer. NXDOMAIN answer would get passed through to the client even if its DNSSEC validation failed, instead of sending a SERVFAIL packet. Caching is not affected by this particular bug but see CVE-2019-10191.

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.0% (top 19%)
CISA exploited list	No
Weakness	CWE-20
Published	2019-07-16
Last modified	2026-06-17

Publisher (CNA): Red Hat, Inc. · Vendor: fedoraproject · nic

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2019-07-16 18:15 UTCPublished CVE record published
2026-06-17 02:10 UTCUpdated Record last modified

nic knot resolver UPGRADE

Affected: <= 3.2.0 · >= 4.0.0 and < 4.1.0

Fixed in: 4.1.0

Safe to downgrade to: a release before 4.0.0

1. Check installed version

apt-cache policy knot-resolver || rpm -q knot-resolver || knot-resolver --version

2. UPGRADE to 4.1.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade knot-resolver

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade knot-resolver

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 4.0.0 (Debian / Ubuntu)

apt-cache madison knot-resolver sudo apt install knot-resolver=<VERSION_BEFORE_4.0.0> sudo apt-mark hold knot-resolver

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list knot-resolver sudo dnf downgrade knot-resolver-<VERSION_BEFORE_4.0.0> sudo dnf versionlock add knot-resolver

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

fedoraproject fedora MITIGATE

Affected: 29 · 30

Fixed in: no fixed release known

Safe to downgrade to: a release before 29

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2019-10190?

knot resolver: upgrade to 4.1.0; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2019-10190 being exploited?

CVE-2019-10190 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2019-10190 affect?

CVE-2019-10190 affects knot resolver, fedora. Severity is high (CVSS 7.5). A vulnerability was discovered in DNS resolver component of knot resolver through version 3.2.0 before 4.1.0 which allows remote attackers to bypass DNSSEC validation for non-existence answer. NXDOMAIN answer would get passed through to the

How urgent is CVE-2019-10190?

Priority 51/100. High severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2023-46317 HIGH 7.5 UPGRADE Knot Resolver before 5.7.0 performs many TCP reconnections upon receiving certain nonsensical responses from s
CVE-2023-26249 HIGH 7.5 UPGRADE Knot Resolver before 5.6.0 enables attackers to consume its resources, launching amplification attacks and pot
CVE-2022-40188 HIGH 7.5 UPGRADE MITIGATE Knot Resolver before 5.5.3 allows remote attackers to cause a denial of service (CPU consumption) because of a
CVE-2022-32983 MEDIUM 5.3 UPGRADE Knot Resolver through 5.5.1 may allow DNS cache poisoning when there is an attempt to limit forwarding actions
CVE-2021-40083 HIGH 7.5 UPGRADE Knot Resolver before 5.3.2 is prone to an assertion failure, triggerable by a remote attacker in an edge case

References

← Back to latest CVEs