CVE-2017-5384

Severity: medium (CVSS 5.9 v3.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.5% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2018-06-11 · updated 2026-06-17
Weakness: CWE-200

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.

Affected products

Mozilla Firefox: before 51.0 — fixed in 51.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 51.0. Check the vendor advisory for mitigations.

References

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

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