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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| CZ.NIC | knot-resolver | all before 4.1.0 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | knot-resolver | 5.0.1-1 | — |
| Debian 13 | knot-resolver | 5.0.1-1 | — |
| Debian 12 | knot-resolver | 5.0.1-1 | — |
| Debian 10 | knot-resolver | 3.2.1-3+deb10u2 | DLA-3795-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | knot-resolver | 3.2.1-3ubuntu2.2 | USN-7047-1 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 18.04 LTS | knot-resolver | No fix yet | — |
| Ubuntu Pro 16.04 LTS | knot-resolver | No fix yet | — |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | knot-resolver | 4.1.0-r0 | — |
| Alpine v3.23 | knot-resolver | 4.1.0-r0 | — |
| Alpine v3.22 | knot-resolver | 4.1.0-r0 | — |
| Alpine v3.21 | knot-resolver | 4.1.0-r0 | — |
| Alpine v3.20 | knot-resolver | 4.1.0-r0 | — |
Show 9 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | knot-resolver | 4.1.0-r0 | — |
| Alpine v3.18 | knot-resolver | 4.1.0-r0 | — |
| Alpine v3.17 | knot-resolver | 4.1.0-r0 | — |
| Alpine v3.16 | knot-resolver | 4.1.0-r0 | — |
| Alpine v3.15 | knot-resolver | 4.1.0-r0 | — |
| Alpine v3.14 | knot-resolver | 4.1.0-r0 | — |
| Alpine v3.13 | knot-resolver | 4.1.0-r0 | — |
| Alpine v3.12 | knot-resolver | 4.1.0-r0 | — |
| Alpine v3.11 | knot-resolver | 4.1.0-r0 | — |
Advisories 2
- USN-7047-1 knot-resolver vulnerabilities Ubuntu Security Notices (USN) · Apr 27, 2026
- DLA-3795-1 knot-resolver - security update Debian Security (DSA / DLA) · Mar 9, 2026