What’s Vulnerable › Vulnerabilities

CVE-2017-7761

• Severity: medium (CVSS 5.5 v3.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% 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-276

Description

The Mozilla Maintenance Service "helper.exe" application creates a temporary directory writable by non-privileged users. When this is combined with creation of a junction (a form of symbolic link), protected files in the target directory of the junction can be deleted by the Mozilla Maintenance Service, which has privileged access. Note: This attack requires local system access and only affects Windows. Other operating systems are not affected. This vulnerability affects Firefox ESR < 52.2 and Firefox < 54.

Affected products

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

How to fix

Upgrade to a fixed version: Mozilla Firefox 52.2.0, 54.0. 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=1215648
• https://sourceforge.net/p/nsis/bugs/1125/
• https://www.mozilla.org/security/advisories/mfsa2017-15/
• https://www.mozilla.org/security/advisories/mfsa2017-16/
• http://www.securityfocus.com/bid/99057
• http://www.securitytracker.com/id/1038689
• https://bugzilla.mozilla.org/show_bug.cgi?id=1215648
• https://sourceforge.net/p/nsis/bugs/1125/
• https://www.mozilla.org/security/advisories/mfsa2017-15/
• https://www.mozilla.org/security/advisories/mfsa2017-16/

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