CVE-2026-44581

MEDIUM LAB

Next.js: Cross-site scripting in App Router applications using CSP nonces

Title source: cna
STIX 2.1

Exploitation Summary

EIP tracks 2 public exploits for CVE-2026-44581. PoCs published by dwisiswant0, XZ1r0.

AI-analyzed exploit summary This repository contains functional proof-of-concept exploits for multiple Next.js v16.2.4 vulnerabilities, including SSRF, XSS, and cache poisoning. The PoCs are well-documented with technical details, vulnerable code excerpts, and runnable exploit scripts.

Description

Next.js is a React framework for building full-stack web applications. From 13.4.0 to before 15.5.16 and 16.2.5, App Router applications that rely on CSP nonces can be vulnerable to stored cross-site scripting when deployed behind shared caches. In affected versions, malformed nonce values derived from request headers could be reflected into rendered HTML in an unsafe way, allowing an attacker to poison cached responses and cause script execution for later visitors. This vulnerability is fixed in 15.5.16 and 16.2.5.

Exploits (2)

github WORKING POC 127 stars
by dwisiswant0 · pythonpoc
https://github.com/dwisiswant0/next-16.2.4-pocs

This repository contains functional proof-of-concept exploits for multiple Next.js v16.2.4 vulnerabilities, including SSRF, XSS, and cache poisoning. The PoCs are well-documented with technical details, vulnerable code excerpts, and runnable exploit scripts.

Classification
Working Poc 95%
Attack Type
Ssrf | Xss | Dos | Auth Bypass | Cache Poisoning
Complexity
Moderate
Reliability
Reliable
Target: Next.js v16.2.4
No auth needed
Prerequisites: Vulnerable Next.js v16.2.4 installation · Network access to the target
devstral-2 · analyzed May 13, 2026 Full analysis →
github WORKING POC
by XZ1r0 · pythonpoc
https://github.com/XZ1r0/cve-2026-poc-collection/tree/main/other/next-16.2.4-pocs/poc/CVE-2026-44581_GHSA-ffhc-5mcf-pf4q

This repository contains a functional exploit for CVE-2026-44581, a reflected XSS vulnerability in Next.js <16.2.5. The exploit demonstrates how a malformed CSP nonce can break out of the attribute context, allowing arbitrary JavaScript execution.

Classification
Working Poc 100%
Attack Type
Xss
Complexity
Moderate
Reliability
Reliable
Target: Next.js <16.2.5
No auth needed
Prerequisites: Ability to influence the Content-Security-Policy request header
devstral-2 · analyzed May 21, 2026 Full analysis →

References (1)

Core 1
Core References

Scores

CVSS v3 4.7
EPSS 0.0001
EPSS Percentile 1.5%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact partial

Details

CWE
CWE-79
Status published
Products (5)
npm/next 13.4.0 - 15.5.16npm
npm/next 16.0.0 - 16.2.5npm
vercel/next.js 13.4.0 - 15.5.16
vercel/next.js >= 13.4.0, < 15.5.16
vercel/next.js >= 16.0.0, < 16.2.5
Published May 13, 2026
Tracked Since May 13, 2026