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TI-2026-21570 Aliases CVE-2026-27118GHSA-9pq4-5hcf-288c

Cache poisoning in @sveltejs/adapter-vercel

Priority LOW 30CWE-346Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Passive
Attack complexity
Low
Attack requirements
None
Impact type
Security bypass
Confidentiality · integrity · availability
Low · None · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub. Impact type from CWE-346.

Summary

SvelteKit is a framework for rapidly developing robust, performant web applications using Svelte. Versions of @sveltejs/adapter-vercel prior to 6.3.2 are vulnerable to cache poisoning. An internal query parameter intended for Incremental Static Regeneration (ISR) is accessible on all routes, allowing an attacker to cause sensitive user-specific responses to be cached and served to other users. Successful exploitation requires a victim to visit an attacker-controlled link while authenticated. Existing deployments are protected by Vercel's WAF, but users should upgrade as soon as possible. This vulnerability is fixed in 6.3.2.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00276 20th percentileScored 2026-11-07
Fix Fixed kit (sveltejs): 6.3.2@sveltejs/adapter-vercel (npm): 6.3.2

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
sveltejskitbefore 6.3.26.3.2Patch availableCNA
—@sveltejs/adapter-vercel (npm)before 6.3.26.3.2Patch availableGHSA-9pq4-5hcf-288c
  • kit Vendorsveltejs Affected before 6.3.2 Fixed in 6.3.2 Patch available CNA
  • @sveltejs/adapter-vercel (npm) Vendor— Affected before 6.3.2 Fixed in 6.3.2 Patch available GHSA-9pq4-5hcf-288c

Remediation

  • Fix · CNA kit (sveltejs) Fixed in 6.3.2
  • Fix · GHSA-9pq4-5hcf-288c @sveltejs/adapter-vercel (npm) Fixed in 6.3.2 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-27118
  2. 2026-10-03 Alias added: GHSA-9pq4-5hcf-288c

References

Advisory 1

Other 2

  • TI-2023-13469 SvelteKit framework has Insufficient CSRF protection for CORS requests CVSS 3.1HIGH 8.8
  • TI-2023-13464 SvelteKit has Insufficient Cross-Site Request Forgery Protection CVSS 3.1HIGH 8.8
  • TI-2024-15660 Sending a GET or HEAD request with a body crashes SvelteKit CVSS 3.1HIGH 7.5
  • TI-2024-30159 Potential mXSS vulnerability due to improper HTML escaping in svelte CVSS 3.1MEDIUM 6.1
  • TI-2025-23466 SvelteKit allows XSS via tracked search_params CVSS 3.1MEDIUM 5.4
  • TI-2025-13940 Svelte 5.46.0 - Hydratable Key Script-Breakout XSS (SSR) CVSS 4.0MEDIUM 5.3
See all 50 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences