CVE-2026-42533: NGINX Map directive and Regex matching vulnerability

highpublic exploitCVSS 8.1CVE-2026-42533

CSIRTS triage

vendor: NGINX product: NGINXOther

What: There is a vulnerability in the Map directive and Regex matching.
Who is affected: Deployments of NGINX are affected.
Urgency: Remediation is urgent due to the high severity and potential for exploitation.
Action: Update to the latest version to mitigate the vulnerability.

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

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Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: high — CVSS 8.1
Published: 2026-07-14
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42533

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.

Moderate exploitation riskCVE-2026-425333.6% 30-day exploitation probability. Patch within normal cadence, watch for KEV listing. Riskier than 88% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-42533	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

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

high[NEW] [high] NGINX NGINX Plus: Multiple vulnerabilitiescert-bund
unknownUSN-8563-2: nginx regressionubuntu
unknownUSN-8563-1: nginx vulnerabilitiesubuntu
unknownMultiple vulnerabilities in F5 products (July 16, 2026)cert-fr-avis
highCVE-2026-42533: A vulnerability exists in NGINX Plus and NGINX Open Source when a map directive uses regex mat…nvd

Recent advisories for NGINX Map directive

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-2026-42533: A vulnerability exists in NGINX Plus and NGINX Open Source when a map directive uses regex mat…nvd · 2026-07-15