What’s Vulnerable › Vulnerabilities

CVE-2017-7755

• Severity: high (CVSS 7.8 v3.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2018-06-11 · updated 2026-06-17
• Weakness: CWE-426

Description

The Firefox installer on Windows can be made to load malicious DLL files stored in the same directory as the installer when it is run. This allows privileged execution if the installer is run with elevated privileges. Note: This attack only affects Windows operating systems. Other operating systems are unaffected. This vulnerability affects Firefox < 54, Firefox ESR < 52.2, and Thunderbird < 52.2.

Affected products

• Mozilla Firefox: before 52.2.0; before 54.0 — fixed in 52.2.0, 54.0
• Mozilla Thunderbird: before 52.2.0 — fixed in 52.2.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 52.2.0, 54.0; Mozilla Thunderbird 52.2.0. Check the vendor advisory for mitigations.

References

• http://www.securityfocus.com/bid/99057
• http://www.securitytracker.com/id/1038689
• https://bugzilla.mozilla.org/show_bug.cgi?id=1361326
• https://www.mozilla.org/security/advisories/mfsa2017-15/
• https://www.mozilla.org/security/advisories/mfsa2017-16/
• https://www.mozilla.org/security/advisories/mfsa2017-17/
• http://www.securityfocus.com/bid/99057
• http://www.securitytracker.com/id/1038689
• https://bugzilla.mozilla.org/show_bug.cgi?id=1361326
• https://www.mozilla.org/security/advisories/mfsa2017-15/
• https://www.mozilla.org/security/advisories/mfsa2017-16/
• https://www.mozilla.org/security/advisories/mfsa2017-17/

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