CVE-2026-13204: Unexpected exit in certain situations with NSEC and NSEC3 both present

highCVSS 7.5CVE-2026-13204

CSIRTS triage

Other

What: An unexpected exit can occur in certain situations with NSEC and NSEC3 both present.
Who is affected: Deployments using both NSEC and NSEC3 are affected.
Urgency: Remediation is urgent due to the high severity of the vulnerability.
Action: Review and update configurations involving NSEC and NSEC3.

AI-assisted analysis generated from the source advisory — verify against the original.

Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: high — CVSS 7.5
Published: 2026-07-14
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-13204

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-132040.51% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 41% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-13204	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

Recent advisories for Unexpected exit in

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

highCVE-2026-13204: If a provably insecure domain is covered by both an NSEC and NSEC3 record at the parent, and t…nvd · 2026-07-22
highCVE-2026-12617: Record ordering based unexpected exit with CNAME or DNAMEmsrc · 2026-07-14
mediumCVE-2026-10822: Key Record using PRIVATEDNS algorithm may lead to unexpected exitmsrc · 2026-07-14