CVE-2026-24040

Workarounds

Avoid using the addJS method in concurrent server-side environments. If usage is required, ensure requests are processed sequentially (e.g., using a queue) rather than in parallel.

The addJS method in the jspdf Node.js build utilizes a shared module-scoped variable (text) to store JavaScript content. When used in a concurrent environment (e.g., a Node.js web server), this variable is shared across all requests.

If multiple requests generate PDFs simultaneously, the JavaScript content intended for one user may be overwritten by a subsequent request before the document is generated. This results in Cross-User Data Leakage, where the PDF generated for User A contains the JavaScript payload (and any embedded sensitive data) intended for User B.

Typically, this only affects server-side environments, although the same race conditions might occur if jsPDF runs client-side.

import { jsPDF } from "jspdf";

const docA = new jsPDF();
const docB = new jsPDF();

// 1. User A sets their script (stored in shared 'text' variable)
docA.addJS('console.log("Secret A");');

// 2. User B sets their script (overwrites shared 'text' variable)
docB.addJS('console.log("Secret B");');

// 3. User A saves their PDF (reads current 'text' variable)
docA.save("userA.pdf");

// Result: userA.pdf contains "Secret B" instead of "Secret A"

Multiple concurrent operations access a shared resource without proper synchronization, producing unpredictable results depending on timing. Typical impact: TOCTOU exploits, data corruption, or privilege escalation.

Kodem intelligence

The vulnerability has been fixed in [email protected]. The fix moves the shared variable into the function scope, ensuring isolation between instances.

1. What is CVE-2026-24040? CVE-2026-24040 is a medium-severity race condition vulnerability in jspdf (npm), affecting versions <= 4.0.0. It is fixed in 4.1.0. Multiple concurrent operations access a shared resource without proper synchronization, producing unpredictable results depending on timing.
2. Which versions of jspdf are affected by CVE-2026-24040? jspdf (npm) versions <= 4.0.0 is affected.
3. Is there a fix for CVE-2026-24040? Yes. CVE-2026-24040 is fixed in 4.1.0. Upgrade to this version or later.
4. Is CVE-2026-24040 exploitable, and should I be worried? Whether CVE-2026-24040 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
5. What actually determines whether CVE-2026-24040 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
6. How do I fix CVE-2026-24040? Upgrade jspdf to 4.1.0 or later.