CVE-2026-31938

Critical

Published: 18 March 2026

Published

18 March 2026

Modified

18 March 2026

KEV Added

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Patch

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CVSS Score 9.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L

EPSS Score 0.0004 13.4th percentile

Risk Priority 19 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-31938 is a critical-severity Cross-site Scripting (CWE-79) vulnerability in Parall Jspdf. Its CVSS base score is 9.6 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 13.4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified are NIST 800-53 SI-10 (Information Input Validation) and SI-2 (Flaw Remediation).

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploit Public-Facing Application (T1190) and 1 other technique. What defenders deploy: see the NIST 800-53 controls recommended below.

Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

SI-2 Flaw Remediation good match

prevent

SI-2 requires identifying, reporting, and correcting system flaws, directly addressing this CVE by patching jsPDF to the fixed version 4.2.1.

SI-10 Information Input Validation good match

prevent

SI-10 mandates validation of information inputs, preventing attackers from injecting malicious options into the unsanitized jsPDF output function.

SI-15 Information Output Filtering partial match

prevent

SI-15 enforces filtering of information outputs, mitigating injection of arbitrary HTML/scripts into the generated PDF opened in the browser context.

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

T1059.007 JavaScript Execution

Adversaries may abuse various implementations of JavaScript for execution.

attack.mitre.org →

Why these techniques?

XSS in jsPDF output() enables arbitrary JS execution in browser (T1059.007) and exploitation of a network-accessible web app/library (T1190).

Confidence: HIGH · MITRE ATT&CK Enterprise v18.1

NVD Description

jsPDF is a library to generate PDFs in JavaScript. Prior to version 4.2.1, user control of the `options` argument of the `output` function allows attackers to inject arbitrary HTML (such as scripts) into the browser context the created PDF is…

opened in. The vulnerability can be exploited in the following scenario: the attacker provides values for the output options, for example via a web interface. These values are then passed unsanitized (automatically or semi-automatically) to the attack victim. The victim creates and opens a PDF with the attack vector using one of the vulnerable method overloads inside their browser. The attacker can thus inject scripts that run in the victims browser context and can extract or modify secrets from this context. The vulnerability has been fixed in jspdf@4.2.1. As a workaround, sanitize user input before passing it to the output method.

Deeper analysisAI

CVE-2026-31938 is a cross-site scripting (XSS) vulnerability, classified under CWE-79, affecting the jsPDF JavaScript library for generating PDFs in versions prior to 4.2.1. The issue stems from insufficient sanitization of the user-controlled `options` argument passed to the `output` function, enabling attackers to inject arbitrary HTML, including scripts, into the browser context where the generated PDF is opened. The vulnerability carries a CVSS v3.1 base score of 9.6 (AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L), reflecting its high severity due to network accessibility, low attack complexity, and potential for significant confidentiality, integrity, and availability impacts.

An attacker can exploit this vulnerability by supplying malicious values for the `output` options, for instance through a web interface where users submit parameters. These unsanitized values are then passed—either automatically or semi-automatically—to a victim who uses one of the vulnerable `output` method overloads to create and open the PDF in their browser. Successful exploitation allows the injected scripts to execute in the victim's browser context, enabling the attacker to extract or modify sensitive data from that context.

The jsPDF security advisory (GHSA-wfv2-pwc8-crg5), release notes for version 4.2.1, and the fixing commit (87a40bbd07e6b30575196370670b41f264aa78d7) confirm the vulnerability has been patched in jsPDF 4.2.1. As a workaround, developers should sanitize all user input before passing it to the `output` method.