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MEDIUM severity

Next.js has cache poisoning in SSG/ISR rendering that leads to cross-user content substitution and persistent denial of serviceGHSA-mcj8-r9mp-w47p

MEDIUMFix: vercel/next.js@52c94ab

GHSA-mcj8-r9mp-w47p is a medium-severity (CVSS 4.8) CWE-524 vulnerability in next. A fix is available for next — see the affected versions and patch details below.

Also known asCVE-2026-94484
Published
Updated
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Oct 24, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-mcj8-r9mp-w47p.

EPSS Exploitation Probability

via FIRST.org ↗
0.2%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs15th percentile — riskier than 15% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

GHSA-mcj8-r9mp-w47p by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 394,803 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

2 pkgs affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

61Kother npm packages depend on this — each one inherits the vulnerability until it's patched upstream
nextnpm
44.6Mdownloads / week

Description

Next.js is a React framework for building full-stack web applications. From 15.0.0 until 15.5.27 and 16.3.8, applications with a root-level catch-all page and statically generated or Incremental Static Regeneration routes can use a shared response cache key that is insufficiently scoped to the source route. A single unauthenticated crafted request can poison that cache, causing cross-user content substitution or persistent denial of service until the poisoned entry is revalidated or replaced. This issue is fixed in versions 15.5.27 and 16.3.8.

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
📦npmnext≥ 16.0.0&&< 16.3.816.3.8npm install next@16.3.8
📦npmnext≥ 15.0.0&&< 15.5.2715.5.27npm install next@15.5.27

Affected Products

1 product · 2 configurations
Application
next.jsvercel
≥ 16.0.0 && < 16.3.8
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for next, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update next to 16.3.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-mcj8-r9mp-w47p is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

Next.js applications that use a root-level catch-all page together with statically generated or Incremental Static Regeneration routes can have their shared response cache poisoned by a single unauthenticated crafted request.
O3 Security · Impact-Aware SCA

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Next.js has cache poisoning in SSG/ISR rendering that…