# CVE-2026-42840: ERPNext 16.16.0 - Stored XSS in POS customer section via unescaped template literals

> Authenticated users can inject malicious scripts into customer fields, leading to stored XSS execution in the POS interface for other operators.

- **Severity:** Medium 5.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 3 Jun 2026
- **Updated:** 3 Jun 2026
- **Also known as:** GHSA-w2pq-xvqr-7fqw

## What is CVE-2026-42840?

CVE-2026-42840 is a medium-severity cross-site scripting vulnerability in Frappe ERPNext, published on 3 Jun 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

An authenticated user can persist arbitrary HTML/JavaScript in the email_id or mobile_no fields of a Customer record and trigger unescaped rendering in the Point of Sale (POS) interface for every operator who selects that customer.
This issue affects ERPNext: 16.16.0.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-42840?


## How do I fix CVE-2026-42840?

No fix has been published for CVE-2026-42840 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-42840 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-42840 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-42840 and fix it if it is affected.

What it is: CVE-2026-42840 is a medium-severity cross-site scripting vulnerability in Frappe ERPNext, published on 3 Jun 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-42840 exists.

Affected product: Frappe ERPNext. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-42840/ (Markdown: https://insights.sbomify.com/CVE-2026-42840/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-42840
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-42840
- OSV: https://osv.dev/vulnerability/CVE-2026-42840

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-42840/
Summaries are generated and may contain mistakes; the official description above is the record.