What’s Vulnerable › Vulnerabilities

CVE-2018-18500

• Severity: critical (CVSS 9.8 v3.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 12.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2019-02-05 · updated 2026-06-17
• Weakness: CWE-416

Description

A use-after-free vulnerability can occur while parsing an HTML5 stream in concert with custom HTML elements. This results in the stream parser object being freed while still in use, leading to a potentially exploitable crash. This vulnerability affects Thunderbird < 60.5, Firefox ESR < 60.5, and Firefox < 65.

Affected products

• Canonical Ubuntu Linux: 14.04, 16.04, 18.04, 18.10
• Debian Linux: 8.0, 9.0
• Mozilla Firefox: before 65.0 — fixed in 65.0
• Mozilla Firefox ESR: before 60.5 — fixed in 60.5
• Mozilla Thunderbird: before 60.5 — fixed in 60.5
• RedHat Enterprise Linux Desktop: 6.0, 7.0
• RedHat Enterprise Linux Server: 6.0, 7.0
• RedHat Enterprise Linux Server Aus: 7.6
• RedHat Enterprise Linux Server Eus: 7.6
• RedHat Enterprise Linux Server Tus: 7.6
• RedHat Enterprise Linux Workstation: 6.0, 7.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 65.0; Mozilla Firefox ESR 60.5; Mozilla Thunderbird 60.5. Check the vendor advisory for mitigations.

References

• http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00021.html
• http://www.securityfocus.com/bid/106781
• https://access.redhat.com/errata/RHSA-2019:0218
• https://access.redhat.com/errata/RHSA-2019:0219
• https://access.redhat.com/errata/RHSA-2019:0269
• https://access.redhat.com/errata/RHSA-2019:0270
• https://lists.debian.org/debian-lts-announce/2019/01/msg00025.html
• https://lists.debian.org/debian-lts-announce/2019/02/msg00024.html
• https://security.gentoo.org/glsa/201903-04
• https://security.gentoo.org/glsa/201904-07
• https://usn.ubuntu.com/3874-1/
• https://usn.ubuntu.com/3897-1/

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