How severe is CVE-2021-43862?

CVE-2021-43862 has a CVSS score of 5.4/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2021-43862?

CVE-2021-43862 affects the following packages: jquery.terminal (npm). Ecosystems affected: npm.

How do I fix CVE-2021-43862?

Update jquery.terminal to 2.31.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-43862 is resolved across your whole dependency graph.

How do I detect CVE-2021-43862 in my npm dependencies?

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

How do I mitigate CVE-2021-43862 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-2021-43862 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2021-43862, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2021-43862?

CVE-2021-43862 has an EPSS (Exploit Prediction Scoring System) score of 1.0%, placing it in the 63th 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-2021-43862?

CVE-2021-43862 is classified as CWE-80 (CWE-80), Cross-site Scripting (XSS) (CWE-79). These weakness types 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-2021-43862 published, and has it been updated?

CVE-2021-43862 was published on December 30, 2021 and was last updated on July 9, 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-2021-43862 — jquery.terminal

MEDIUMFix: jcubic/jquery.terminal@77eb044

CVE-2021-43862 is a medium-severity (CVSS 5.4) CWE-80 vulnerability in jquery.terminal. 1 public exploit reference exists, so weaponization risk is real. A fix is available for jquery.terminal — see the affected versions and patch details below.

jquery.terminal self XSS on user input

Also known asGHSA-x9r5-jxvq-4387

Published

Dec 30, 2021

Updated

Jul 9, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

Exploitation data as of Oct 11, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.0%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs63th percentile — riskier than 63% of all scored CVEsHighest risk

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

How urgent is this, really

CVE-2021-43862 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg 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.

14other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

jquery.terminalnpm

6Kdownloads / week

Description

Impact

This is low impact and limited XSS, because code for XSS payload is always visible, but attacker can use other techniques to hide the code the victim sees.

Also if the application use execHash option and execute code from URL the attacker can use this URL to execute his code. The scope is limited because the javascript code inside html attribute used is added to span tag, so no automatic execution like with onerror on images is possible.

Patches

Fixed version 2.31.1

Workarounds

The user can use formatting that wrap whole user input and it's no op.

$.terminal.new_formatter([/([\s\S]+)/g, '[[;;]$1]']);

The fix will only work when user of the library is not using different formatters (e.g. to highlight code in different way).

References

The issue was reported here jcubic/jquery.terminal#727

For more information

If you have any questions or comments about this advisory:

Open an issue in jcubic/jquery.terminal
Email us at [email protected]

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`jquery.terminal`	all versions	2.31.1`npm install jquery.terminal@2.31.1`

Affected Products

1 product · 1 configurations

Application

jquery.terminaljquery.terminal_project

< 2.31.1

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

jQuery Terminal Emulator is a plugin for creating command line interpret…

github.comNVDJan 2022

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for jquery.terminal, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update jquery.terminal to 2.31.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-43862 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.

Frequently Asked Questions

### Impact This is low impact and limited XSS, because code for XSS payload is always visible, but attacker can use other techniques to hide the code the victim sees. Also if the application use execHash option and execute code from URL the attacker can use this URL to execute his code. The scope is limited because the javascript code inside html attribute used is added to span tag, so no automatic execution like with `onerror` on images is possible. ### Patches Fixed version 2.31.1 ### Workarounds The user can use formatting that wrap whole user input and it's no op. ```javascript $.termi