CVE-2026-75604: Next.js: Unauthenticated Remote Code Execution on windows-hosted servers

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 2.1%, percentile 82: FIRST’s model estimates a 2.1% chance of exploitation activity in the next 30 days, higher than 82% of all scored CVEs (elevated). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes next (npm) >= 13.4.0, < 15.5.24, fixed in 15.5.24; next (npm) >= 16.0.0, < 16.3.3, fixed in 16.3.3. Check your lockfile, including transitive dependencies.
• Editorial verdict: Patch this week. Next.js: Windows, AVIF and next/og RCEs (Aug-Sep 2026) — Self-hosted Next.js apps still below 15.5.24 or 16.3.3 should upgrade now, ideally straight to the October releases; Windows hosts and apps optimizing untrusted AVIF images are the urgent cases.

What it is

Next.js is a React framework for building full-stack web applications. From 13.4.0 until 15.5.24 and 16.3.3, Next.js applications using Pages Router or App Router without Cache Components on Windows-hosted servers do not consistently escape backslashes in route segments before constructing incremental-cache paths. In packages/next/src/shared/lib/router/utils/escape-path-delimiters.ts and packages/next/src/server/lib/incremental-cache/file-system-cache.ts, a remote request can supply encoded Windows path separators that traverse outside the intended cache root and expose private build data, including the server-reference-manifest encryption key. Disclosure of that key can enable remote code execution in the affected application. This issue is fixed in versions 15.5.24 and 16.3.3.

From the GitHub advisory

Impact

A vulnerability in applications using Pages and App router without Cache Component can lead to remote code execution when the server is hosted on machines using a Windows filesystem.

Workaround

There is no known workaround for affected windows-hosted applications. You should upgrade immediately if your server is hosted on Windows.

Weakness type: CWE-22.

Product: next (npm) · Assigned by: GitHub_M · Published: 2026-09-01

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: high (needs special conditions)
• Privileges required: none (no login)
• User interaction: none
• Scope: changed (can affect other components)

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-21): 2.10% probability of exploitation activity in the next 30 days; percentile 82.

Timeline

• 2026-08-25 — erroneo.us brief: Next.js: Windows, AVIF and next/og RCEs (Aug-Sep 2026)
• 2026-09-01 — CVE record published by GitHub_M
• 2026-09-04 — CVE record last updated
• 2026-09-08 — GitHub-reviewed advisory GHSA-p293-qw3h-jr36 published (critical)

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-p293-qw3h-jr36 github.com
2. CVE.org record CVE-2026-75604 cve.org
3. NVD entry CVE-2026-75604 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com
4. github.com github.com
5. github.com github.com

Critical npm advisories · Today’s Security Digest