CVE-2026-66374
Heap-based buffer overflow in Knot Resolver DoQ allows remote code execution.
Is CVE-2026-66374 being exploited?
Not confirmed. CVE-2026-66374 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.50% probability of exploitation in the next 30 days.
How severe is CVE-2026-66374?
CVE-2026-66374 is rated High with a CVSS score of 8.1. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-66374?
Yes. A fix has been recorded for CVE-2026-66374. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-66374 affect?
CVE-2026-66374 affects Knot Resolver < 6.4.1, Systems using Knot Resolver for DoQ, DNS resolvers on routers/servers/ISPs using Knot. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-66374?
Upgrade to Knot Resolver 6.4.1+, restrict/monitor DoQ ingress until patched.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote code execution in Knot Resolver via crafted DoQ (DNS-over-QUIC) packets; attacker can execute code as resolver process and disrupt/compromise DNS service.
Immediate action required
- affected< 6.4.1
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.