What’s Vulnerable › Vulnerabilities

CVE-2017-7749

• Severity: critical (CVSS 9.8 v3.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.6% 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-416

Description

A use-after-free vulnerability when using an incorrect URL during the reloading of a docshell. This results in a potentially exploitable crash. This vulnerability affects Firefox < 54, Firefox ESR < 52.2, and Thunderbird < 52.2.

Affected products

• Debian Linux: 8.0, 9.0
• Mozilla Firefox: before 54.0; before 52.2.0 — fixed in 52.2.0, 54.0
• Mozilla Thunderbird: before 52.2.0 — fixed in 52.2.0
• Red Hat Enterprise Linux: 6.0, 7.0
• RedHat Enterprise Linux Desktop: 6.0, 7.0
• RedHat Enterprise Linux Server: 6.0, 7.0
• RedHat Enterprise Linux Server Aus: 7.3, 7.4
• RedHat Enterprise Linux Server Eus: 7.3, 7.4, 7.5
• RedHat Enterprise Linux Workstation: 6.0, 7.0

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://access.redhat.com/errata/RHSA-2017:1440
• https://access.redhat.com/errata/RHSA-2017:1561
• https://bugzilla.mozilla.org/show_bug.cgi?id=1355039
• https://www.debian.org/security/2017/dsa-3881
• https://www.debian.org/security/2017/dsa-3918
• 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

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