CVE-2026-44578Public exploitNetwork attack vector

Server-side request forgery via unsafe WebSocket upgrades

Published May 13, 2026 · Updated May 13, 2026

Server-side request forgery in Vercel Next.js 13.4.13 through 15.5.15 and 16.0.0 through 16.2.4 allows remote attackers to reach arbitrary hosts. WebSocket upgrade handling proxies attacker-selected destinations without the safety checks that restrict normal HTTP external rewrites. The flaw requires a self-hosted application using the built-in Node.js server; Vercel-hosted deployments are unaffected, and successful requests can expose internal services or cloud metadata.

CVSS severity8.6
High
EPSS probability38.87%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Server-side request forgery in Vercel Next.js 13.4.13 through 15.5.15 and 16.0.0 through 16.2.4 allows remote attackers to reach arbitrary hosts. WebSocket upgrade handling proxies attacker-selected destinations without the safety checks that restrict normal HTTP external rewrites. The flaw requires a self-hosted application using the built-in Node.js server; Vercel-hosted deployments are unaffected, and successful requests can expose internal services or cloud metadata.

The record

CVE
CVE-2026-44578
Published
May 13, 2026
Updated
May 13, 2026
Vendor
Vercel
Product
Next.js
Classifications
CWE-918, T1552.005
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 13, 2026CVE publishedPublication date reported by the CVE source.
  2. May 13, 2026Record 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=>= 13.4.13, < 15.5.16
  2. Affected versionversion=>= 16.0.0, < 16.2.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Vercel · Next.jsversion=>= 13.4.13, < 15.5.16; version=>= 16.0.0, < 16.2.5

Published CVSS scores

8.6GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/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 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 exploitPublished

Weakness, pattern, technique

CWE-918Server-Side Request Forgery (SSRF)
T1552.005Unsecured Credentials Cloud Instance Metadata API

Public exploit references

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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