CVE-2025-49826Network attack vector

Service interruption via shared-response cache poisoning

Published Jul 3, 2025 · Updated Jul 8, 2025

Cache poisoning in Vercel Next.js 15.0.4-canary.51 through 15.1.7 allows remote attackers to interrupt access to static pages. The response-cache path reuses a shared response object during concurrent ISR and SSR requests, allowing an HTTP 204 status to enter the static-page cache. Exploitation requires self-hosting with cache revalidation, an SSR route, and a CDN that caches 204 responses; affected pages then return empty responses to all users.

CVSS severity7.5
High
EPSS probability1.09%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cache poisoning in Vercel Next.js 15.0.4-canary.51 through 15.1.7 allows remote attackers to interrupt access to static pages. The response-cache path reuses a shared response object during concurrent ISR and SSR requests, allowing an HTTP 204 status to enter the static-page cache. Exploitation requires self-hosting with cache revalidation, an SSR route, and a CDN that caches 204 responses; affected pages then return empty responses to all users.

The record

CVE
CVE-2025-49826
Published
Jul 3, 2025
Updated
Jul 8, 2025
Vendor
Vercel
Product
Next.js
Classifications
CWE-444, T1499
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

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Is a vulnerable build present?

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

  1. Affected versionversion=>= 15.0.4-canary.51, < 15.1.8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Vercel · Next.jsversion=>= 15.0.4-canary.51, < 15.1.8

Published CVSS scores

7.5GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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

Technologies

Your stack

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Your stack

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