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CVE-2018-18500

CRITICAL

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.

Published: Feb 5, 2019 Modified: Jun 17, 2026
CWE-416

CVSS Metrics

CVSSv3
Attack Vector: NETWORK Attack Complexity: LOW Privileges Required: NONE User Interaction: NONE Scope: UNCHANGED Confidentiality Impact: HIGH Integrity Impact: HIGH Availability Impact: HIGH

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected Products (18)

Vendor Product Version
mozilla firefox * < 65.0
mozilla firefox_esr * < 60.5
mozilla thunderbird * < 60.5
canonical ubuntu_linux 14.04
canonical ubuntu_linux 16.04
canonical ubuntu_linux 18.04
canonical ubuntu_linux 18.10
debian debian_linux 8.0
debian debian_linux 9.0
redhat enterprise_linux_desktop 6.0
redhat enterprise_linux_desktop 7.0
redhat enterprise_linux_server 6.0
redhat enterprise_linux_server 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
redhat enterprise_linux_workstation 7.0

GitHub Security Advisory GHSA-6hxm-h9g7-cg3m

A use-after-free vulnerability can occur while parsing an HTML5 stream in concert with custom...

Risk Scores

CVSS Score 9.8 / 10
EPSS Score 12.66%

Top 4% most likely to be exploited

Threat Score 43 / 100

Data Sources

NVD EPSS GitHub