CVE-2025-49005Public exploitNetwork attack vector

Cache poisoning via omitted RSC Vary header

Published Jul 3, 2025 · Updated Jul 8, 2025

Cache poisoning in Vercel Next.js App Router 15.3.0 through 15.3.2 allows remote attackers to serve RSC payloads instead of HTML. The base server omits RSC and router request headers from Vary, so middleware redirects that strip the _rsc cache-buster let browsers or CDNs reuse an RSC response for an HTML URL. Exploitation requires App Router middleware rewrites or redirects; Vercel deployments affect browser caches only, while external self-hosted CDNs can cache incorrect content.

CVSS severity3.7
Low
EPSS probability0.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Cache poisoning in Vercel Next.js App Router 15.3.0 through 15.3.2 allows remote attackers to serve RSC payloads instead of HTML. The base server omits RSC and router request headers from Vary, so middleware redirects that strip the _rsc cache-buster let browsers or CDNs reuse an RSC response for an HTML URL. Exploitation requires App Router middleware rewrites or redirects; Vercel deployments affect browser caches only, while external self-hosted CDNs can cache incorrect content.

The record

CVE
CVE-2025-49005
Published
Jul 3, 2025
Updated
Jul 8, 2025
Vendor
Vercel
Product
Next.js
Classifications
CWE-444, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 3, 2025CVE publishedPublication date reported by the CVE source.
  2. Jul 8, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 15.3.0, < 15.3.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Vercel · Next.jsversion=>= 15.3.0, < 15.3.3

Published CVSS scores

3.7GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo