How severe is CVE-2026-44581?

CVE-2026-44581 has a CVSS score of 4.7/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2026-44581?

CVE-2026-44581 affects the following packages: next (npm), next (npm). Ecosystems affected: npm.

How do I fix CVE-2026-44581?

Update next to 15.5.16 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-44581 is resolved across your whole dependency graph.

How do I detect CVE-2026-44581 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for next, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-44581 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is CVE-2026-44581 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-44581 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-44581?

CVE-2026-44581 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 13th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-44581?

CVE-2026-44581 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2026-44581 published, and has it been updated?

CVE-2026-44581 was published on May 13, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm

Not in CISA KEV

MEDIUM severity

CVE-2026-44581 — next

MEDIUM

CVE-2026-44581 is a medium-severity (CVSS 4.7) Cross-site Scripting (XSS) vulnerability in next. A fix is available for next — see the affected versions and patch details below.

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

Also known asGHSA-ffhc-5mcf-pf4q

Published

May 13, 2026

Updated

Oct 28, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-44581.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs13th percentile — riskier than 13% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

2 pkgs affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

61Kother npm packages depend on this — each one inherits the vulnerability until it's patched upstream

nextnpm

91.6Mdownloads / week

Description

Impact

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.

Fix

We now reject or ignore malformed nonce values before they are embedded into HTML and apply stricter nonce sanitization so request-derived nonce data cannot break out of the intended attribute context.

Workarounds

If you cannot upgrade immediately, strip inbound Content-Security-Policy request headers from untrusted traffic.

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`next`	≥ 13.4.0&&< 15.5.16	15.5.16`npm install next@15.5.16`
📦npm	`next`	≥ 16.0.0&&< 16.2.5	16.2.5`npm install next@16.2.5`

Affected Products

1 product · 2 configurations

Application

next.jsvercel

≥ 16.0.0 && < 16.2.5

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for next, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update next to 15.5.16 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-44581 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

Moderate: This stored cross-site scripting (XSS) flaw in Next.js, a component used in Red Hat AMQ, arises from improper handling of malformed Content Security Policy (CSP) nonce values. When App Router applications are deployed behind shared caches and rely on CSP nonces, an attacker can inject malicious scripts into…

Workaround published by Red Hat

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

Source: Red Hat security advisory for CVE-2026-44581 (CC BY 4.0)

Frequently Asked Questions

### Impact 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. ### Fix We now reject or ignore malformed nonce values before they are embedded into HTML and apply stricter nonce sanitization so request-derived nonce data cannot break out of the intended attribute context. ### Workarounds