CVE-2026-44580Network attack vector

Cross-site scripting via unsafe script serialization

Published May 13, 2026 · Updated May 13, 2026

Cross-site scripting in Vercel Next.js allows remote attackers to execute arbitrary JavaScript in visitors' browsers through crafted content. Next.js embeds serialized beforeInteractive script content into the document without HTML-escaping attacker-controlled values, allowing the data to escape the inline script boundary. Exploitation requires an affected application to combine beforeInteractive scripts with untrusted content and a visitor to load the resulting page.

CVSS severity6.1
Medium
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in Vercel Next.js allows remote attackers to execute arbitrary JavaScript in visitors' browsers through crafted content. Next.js embeds serialized beforeInteractive script content into the document without HTML-escaping attacker-controlled values, allowing the data to escape the inline script boundary. Exploitation requires an affected application to combine beforeInteractive scripts with untrusted content and a visitor to load the resulting page.

The record

CVE
CVE-2026-44580
Published
May 13, 2026
Updated
May 13, 2026
Vendor
Vercel
Product
Next.js
Classifications
CWE-79, T1189
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

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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=>= 13.0.0, < 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=>= 13.0.0, < 15.5.16; version=>= 16.0.0, < 16.2.5

Published CVSS scores

6.1GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/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 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-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1189Drive-by Compromise

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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