CVE-2021-40083: nic knot_resolver Reachable Assertion
CVSS: 7.5v3.1HighModified
AliasesUBUNTU-CVE-2021-40083DEBIAN-CVE-2021-40083
Published 25-08-2021Last modified 04-08-2024
Vulnerability summary
CVE-2021-40083 is a high (CVSS 7.5) Reachable Assertion vulnerability in nic knot_resolver. EPSS estimates a 1.42% chance of exploitation in the next 30 days, higher than 72.4% of scored vulnerabilities.
CVSS score
7.5/10
010
High · v3.1 (NVD)EPSS score
1.42%
0%100%
Low · 0.00 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Timeline
- 25-08-2021PublishedVulnerability first disclosed.
- 04-08-2024Last modifiedVulnerability information updated.
Description
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).
CVSS metrics
4 scores · 3 sources · 2 versionsHigh 7.5Preferred score · NVD (NIST)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HSourcesAll 3 agree
- OSV · UbuntuEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Medium 5.0Preferred score · NVD (NIST)
AV:N/AC:L/Au:N/C:N/I:N/A:PSourcesSingle source
EPSS trend
Probability
1.42%
Chance of exploitation in the next 30 days
Percentile
72%
Versus all other CVEs
30-day change
0.00 pp
From 1.42% on 18-09-2026
18-09-202618-10-2026
EPSS score1.42%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Debian1 product
- knot-resolver< 5.4.1-2
Nic1 product
- knot_resolver< 5.3.2
Ubuntu1 product
- knot-resolver< 5.4.4-1
3 vendors · 3 products
References
4 links- gitlab.nic.cz/knot/knot-resolver/-/merge_requests/1169X Refsource MISCREPORTPatchThird Party Advisory
