CVE-2021-40083
Knot Resolver before 5.3.2 is prone to an assertion failure, triggerable by a remote attacker in...
Knot Resolver before 5.3.2 is prone to an assertion failure, triggerable by a remote attacker in an edge case (NSEC3 with too many iterations used for a positive wildcard proof).
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
NVD Score used
Knot Resolver before 5.3.2 is prone to an assertion failure, triggerable by a remote attacker in an edge case (NSEC3 with too many iterations used for a positive wildcard proof).
- Record
CVE-2021-40083- 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 2.0
- 5.0 Medium
AV:N/AC:L/Au:N/C:N/I:N/A:P - Weakness
- CWE-617
- Updated
- 2026-11-02
CVE List No score
Knot Resolver before 5.3.2 is prone to an assertion failure, triggerable by a remote attacker in an edge case (NSEC3 with too many iterations used for a positive wildcard proof).
- Record
CVE-2021-40083- Updated
- 2026-11-02
EUVDEUVD-2021-27273 No score
Knot Resolver before 5.3.2 is prone to an assertion failure, triggerable by a remote attacker in an edge case (NSEC3 with too many iterations used for a positive wildcard proof).
- Record
EUVD-2021-27273- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-wvjr-27w9-ff2r No score
Knot Resolver before 5.3.2 is prone to an assertion failure, triggerable by a remote attacker in...
Knot Resolver before 5.3.2 is prone to an assertion failure, triggerable by a remote attacker in an edge case (NSEC3 with too many iterations used for a positive wildcard proof).
- Record
GHSA-wvjr-27w9-ff2r- Weakness
- CWE-617
- Updated
- 2026-11-02
OSV
Knot Resolver before 5.3.2 is prone to an assertion failure, triggerable by a remote attacker in an edge case (NSEC3 with too many iterations used for a positive wildcard proof).
- Record
CVE-2021-40083- 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-2021-40083
Knot Resolver before 5.3.2 is prone to an assertion failure, triggerable by a remote attacker in an edge case (NSEC3 with too many iterations used for a positive wildcard proof).
- Record
DEBIAN-CVE-2021-40083- 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-2021-40083
Knot Resolver before 5.3.2 is prone to an assertion failure, triggerable by a remote attacker in an edge case (NSEC3 with too many iterations used for a positive wildcard proof).
- Record
UBUNTU-CVE-2021-40083- 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
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
knot-resolverDebian:12 |
before 5.4.1-2 | 5.4.1-2 |
knot-resolverDebian:13 |
before 5.4.1-2 | 5.4.1-2 |
knot-resolverDebian:14 |
before 5.4.1-2 | 5.4.1-2 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected | ||
| 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-2021-40083 is a high vulnerability (CVSS 7.5) in Nic Knot Resolver, published August 25, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.42%, the 72nd percentile. Fixed in knot-resolver 5.4.1-2.