Authenticated remote code execution in Microsoft DNS Server — widely deployed core infrastructure that can disrupt enterprise networks and services.
CVE-2026-83889
Authenticated RCE in Microsoft DNS Server via invalid pointer release.
Is CVE-2026-83889 being exploited?
Not confirmed. CVE-2026-83889 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 0.91% probability of exploitation in the next 30 days.
How severe is CVE-2026-83889?
CVE-2026-83889 is rated High with a CVSS score of 8.8. 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-2026-83889?
Yes. A fix has been recorded for CVE-2026-83889. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-83889 affect?
CVE-2026-83889 affects Microsoft DNS Server, Windows Server (DNS role). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-83889?
Apply Microsoft security update to DNS servers immediately; isolate until patched.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Authenticated attacker can execute arbitrary code on DNS servers, leading to full system compromise, persistence and lateral movement.
Immediate action required
- affected>= 10.0.14393.0 and < 10.0.14393.9612
- affected>= 10.0.17763.0 and < 10.0.17763.9376
- affected>= 10.0.19044.0 and < 10.0.19044.7807
- affected>= 10.0.19045.0 and < 10.0.19044.7807
- affected>= 10.0.22631.0 and < 10.0.22631.7652
- affected>= 10.0.22631.0 and < 10.0.22631.7652
- affected>= 10.0.26100.0 and < 10.0.26100.9711
- affected>= 10.0.26200.0 and < 10.0.26200.9711
- affected>= 10.0.28000.0 and < 10.0.28000.3231
- affected>= 10.0.26300.0 and < 10.0.26300.9711
- affected>= 6.2.9200.0 and < 6.2.9200.26434
- affected>= 6.3.9600.0 and < 6.3.9600.23470
- affected>= 6.3.9600.0 and < 6.3.9600.23470
- affected>= 6.2.9200.0 and < 6.2.9200.26434
- affected>= 10.0.14393.0 and < 10.0.14393.9612
- affected>= 10.0.14393.0 and < 10.0.14393.9612
- affected>= 10.0.17763.0 and < 10.0.17763.9376
- affected>= 10.0.17763.0 and < 10.0.17763.9376
- affected>= 10.0.20348.0 and < 10.0.20348.5761
- affected>= 10.0.26100.0 and < 10.0.26100.33650
- affected>= 10.0.26100.0 and < 10.0.26100.33650
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.