CVE-2019-19331
knot-resolver before version 4.3.0 is vulnerable to denial of service through high CPU...
knot-resolver before version 4.3.0 is vulnerable to denial of service through high CPU utilization. DNS replies with very many resource records might be processed very inefficiently, in extreme cases taking even several CPU seconds for each such uncached message. For example, a few thousand A records can be squashed into one DNS message (limit is 64kB).
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
7.5
knot-resolver before version 4.3.0 is vulnerable to denial of service through high CPU utilization. DNS replies with very many resource records might be processed very inefficiently, in extreme cases taking even several CPU seconds for each such uncached message. For example, a few thousand A records can be squashed into one DNS message (limit is 64kB).
- Record
CVE-2019-19331- CVSS 3.0
- 7.5 High
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-407
- Updated
- 2026-11-02
EUVDEUVD-2019-8952
7.5
knot-resolver before version 4.3.0 is vulnerable to denial of service through high CPU utilization. DNS replies with very many resource records might be processed very inefficiently, in extreme cases taking even several CPU seconds for each such uncached message. For example, a few thousand A records can be squashed into one DNS message (limit is 64kB).
- Record
EUVD-2019-8952- CVSS 3.0
- 7.5 High
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-9f7v-8m4p-pv76
7.5
knot-resolver before version 4.3.0 is vulnerable to denial of service through high CPU...
knot-resolver before version 4.3.0 is vulnerable to denial of service through high CPU utilization. DNS replies with very many resource records might be processed very inefficiently, in extreme cases taking even several CPU seconds for each such uncached message. For example, a few thousand A records can be squashed into one DNS message (limit is 64kB).
- Record
GHSA-9f7v-8m4p-pv76- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-404, CWE-407
- Updated
- 2026-11-02
NVD
7.5
knot-resolver before version 4.3.0 is vulnerable to denial of service through high CPU utilization. DNS replies with very many resource records might be processed very inefficiently, in extreme cases taking even several CPU seconds for each such uncached message. For example, a few thousand A records can be squashed into one DNS message (limit is 64kB).
- Record
CVE-2019-19331- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS 3.0
- 7.5 High
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS 2.0
- 5.0 Medium
AV:N/AC:L/Au:N/C:N/I:N/A:P - Weakness
- CWE-407, CWE-404
- Updated
- 2026-11-02
OSVALPINE-CVE-2019-19331
7.5
knot-resolver before version 4.3.0 is vulnerable to denial of service through high CPU utilization. DNS replies with very many resource records might be processed very inefficiently, in extreme cases taking even several CPU seconds for each such uncached message. For example, a few thousand A records can be squashed into one DNS message (limit is 64kB).
- Record
ALPINE-CVE-2019-19331- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-03
OSV
7.5
knot-resolver before version 4.3.0 is vulnerable to denial of service through high CPU utilization. DNS replies with very many resource records might be processed very inefficiently, in extreme cases taking even several CPU seconds for each such uncached message. For example, a few thousand A records can be squashed into one DNS message (limit is 64kB).
- Record
CVE-2019-19331- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVDEBIAN-CVE-2019-19331
7.5
knot-resolver before version 4.3.0 is vulnerable to denial of service through high CPU utilization. DNS replies with very many resource records might be processed very inefficiently, in extreme cases taking even several CPU seconds for each such uncached message. For example, a few thousand A records can be squashed into one DNS message (limit is 64kB).
- Record
DEBIAN-CVE-2019-19331- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVUBUNTU-CVE-2019-19331
7.5
knot-resolver before version 4.3.0 is vulnerable to denial of service through high CPU utilization. DNS replies with very many resource records might be processed very inefficiently, in extreme cases taking even several CPU seconds for each such uncached message. For example, a few thousand A records can be squashed into one DNS message (limit is 64kB).
- Record
UBUNTU-CVE-2019-19331- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS 3.0
- 7.5 High
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVUSN-7047-1 No score
knot-resolver vulnerabilities
Vladimír Čunát discovered that Knot Resolver incorrectly handled input during DNSSEC validation. A remote attacker could possibly use this issue to bypass certain validations. (CVE-2019-10190)
Vladimír Čunát discovered that Knot Resolver incorrectly handled input during DNSSEC validation. A remote attacker could possibly use this issue to downgrade DNSSEC-secure domains to a DNSSEC-insecure state, resulting in a domain hijacking attack. (CVE-2019-10191)
Vladimír Čunát discovered that Knot Resolver incorrectly handled certain DNS replies with many resource records. An attacker could possibly use this issue to consume system resources, resulting in a denial of service. (CVE-2019-19331)
Lior Shafir, Yehuda Afek, and Anat Bremler-Barr discovered that Knot Resolver incorrectly handled certain queries. A remote attacker could use this issue to perform an amplification attack directed at a target. (CVE-2020-12667)
- Record
USN-7047-1- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
knot-resolverAlpine:v3.11 |
before 4.3.0-r0 | 4.3.0-r0 |
knot-resolverAlpine:v3.12 |
before 4.3.0-r0 | 4.3.0-r0 |
knot-resolverAlpine:v3.13 |
before 4.3.0-r0 | 4.3.0-r0 |
knot-resolverAlpine:v3.14 |
before 4.3.0-r0 | 4.3.0-r0 |
knot-resolverAlpine:v3.15 |
before 4.3.0-r0 | 4.3.0-r0 |
knot-resolverAlpine:v3.16 |
before 4.3.0-r0 | 4.3.0-r0 |
knot-resolverAlpine:v3.17 |
before 4.3.0-r0 | 4.3.0-r0 |
knot-resolverAlpine:v3.18 |
before 4.3.0-r0 | 4.3.0-r0 |
knot-resolverAlpine:v3.19 |
before 4.3.0-r0 | 4.3.0-r0 |
knot-resolverAlpine:v3.20 |
before 4.3.0-r0 | 4.3.0-r0 |
Show 11 moreShow less
| Package | Affected | Fixed |
|---|---|---|
knot-resolverAlpine:v3.21 |
before 4.3.0-r0 | 4.3.0-r0 |
knot-resolverAlpine:v3.22 |
before 4.3.0-r0 | 4.3.0-r0 |
knot-resolverAlpine:v3.23 |
before 4.3.0-r0 | 4.3.0-r0 |
knot-resolverAlpine:v3.24 |
before 4.3.0-r0 | 4.3.0-r0 |
knot-resolverDebian:12 |
before 5.0.1-1 | 5.0.1-1 |
knot-resolverDebian:13 |
before 5.0.1-1 | 5.0.1-1 |
knot-resolverDebian:14 |
before 5.0.1-1 | 5.0.1-1 |
knot-resolverDebian:10 |
before 3.2.1-3+deb10u2, plus listed versions 3.2.1-33.2.1-3+deb10u1 |
3.2.1-3+deb10u2 |
knot-resolverUbuntu:Pro:16.04:LTS |
All versions, plus listed versions 1.0.0~beta2-123-g6134920-11.0.0~beta3-11.0.0~beta3-1ubuntu0.1~esm1 |
None known |
knot-resolverUbuntu:Pro:18.04:LTS |
All versions, plus listed versions 1.3.3-11.5.0-41.5.1-11.5.2-12.0.0-3 Show 4 moreShow less2.1.0-12.1.0-22.1.1-12.1.1-1ubuntu0.1~esm2 |
None known |
knot-resolverUbuntu:20.04:LTS |
before 3.2.1-3ubuntu2.2, plus listed versions 3.2.1-33.2.1-3ubuntu13.2.1-3ubuntu23.2.1-3ubuntu2.1 |
3.2.1-3ubuntu2.2 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, aliases, references | OSV | |
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2019-19331 is a high vulnerability (CVSS 7.5) in Cz.nic Knot-resolver, published December 16, 2019. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 2.11%, the 81st percentile. Fixed in knot-resolver 4.3.0-r0.
References
bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-19331
knot-resolver.cz/2019-12-04-knot-resolver-4.3.0.html
lists.debian.org/debian-lts-announce/2024/04/msg00017.html
nvd.nist.gov/vuln/detail/CVE-2019-19331
github.com/advisories/GHSA-9f7v-8m4p-pv76
security.alpinelinux.org/vuln/CVE-2019-19331
Show 8 moreShow less
security-tracker.debian.org/tracker/CVE-2019-19331
ubuntu.com/security/CVE-2019-19331
openwall.com/lists/oss-security/2019/12/04/4
cve.org/CVERecord?id=CVE-2019-19331
ubuntu.com/security/notices/USN-7047-1
ubuntu.com/security/CVE-2019-10190
ubuntu.com/security/CVE-2019-10191
ubuntu.com/security/CVE-2020-12667