What’s Vulnerable › Vulnerabilities

CVE-2017-7801

• 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: yes
• Published: 2018-06-11 · updated 2026-06-17
• Weakness: CWE-416

Description

A use-after-free vulnerability can occur while re-computing layout for a "marquee" element during window resizing where the updated style object is freed while still in use. This results in a potentially exploitable crash. This vulnerability affects Thunderbird < 52.3, Firefox ESR < 52.3, and Firefox < 55.

Affected products

• Debian Linux: 8.0, 9.0
• Mozilla Firefox: before 55.0; before 52.3.0 — fixed in 52.3.0, 55.0
• Mozilla Thunderbird: before 52.3.0 — fixed in 52.3.0
• 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 52.3.0, 55.0; Mozilla Thunderbird 52.3.0. Check the vendor advisory for mitigations.

References

• http://www.securityfocus.com/bid/100197
• http://www.securitytracker.com/id/1039124
• https://access.redhat.com/errata/RHSA-2017:2456
• https://access.redhat.com/errata/RHSA-2017:2534
• https://bugzilla.mozilla.org/show_bug.cgi?id=1371259
• https://security.gentoo.org/glsa/201803-14
• https://www.debian.org/security/2017/dsa-3928
• https://www.debian.org/security/2017/dsa-3968
• https://www.mozilla.org/security/advisories/mfsa2017-18/
• https://www.mozilla.org/security/advisories/mfsa2017-19/
• https://www.mozilla.org/security/advisories/mfsa2017-20/
• http://www.securityfocus.com/bid/100197

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