CVE-2018-18500

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: 2019-02-05 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2018-18500 is rated High Risk (75.2/100): CVSS Critical severity, with high exploitation likelihood (EPSS 35.41%, 97th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +2.00% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2018-18500

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-29 33.41% 35.41% +2.00%
2 2026-05-26 28.23% 33.41% +5.18%
3 2026-01-06 — 28.23% —

Full EPSS history (30 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2018-18500

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.0 CRITICAL
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2018-18500

OS Trackers for CVE-2018-18500

vendor priority summary link
alpine critical CVE-2018-18500: 1 source package rows (firefox-esr); 7 state rows across 7 repos (3.17-community, 3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community); fixed 7, open 0. https://security.alpinelinux.org/vuln/CVE-2018-18500
debian not yet assigned CVE-2018-18500 not yet assigned priority: Debian including 3 source packages (firefox, firefox-esr, thunderbird), 11 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 11. https://security-tracker.debian.org/tracker/CVE-2018-18500
gentoo normal CVE-2018-18500: 2 GLSA(s) (201903-04, 201904-07), 4 atom(s) (mail-client/thunderbird, mail-client/thunderbird-bin, www-client/firefox, www-client/firefox-bin); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2018-18500
redhat critical — https://access.redhat.com/security/cve/CVE-2018-18500
suse medium CVE-2018-18500 severity moderate: SUSE including 184 source package names (1.0.0.1862.1.5.2:libfreebl3-3.41.1-3.13.1, 1.0.0.1862.1.5.2:libsoftokn3-3.41.1-3.13.1, …), 743 product×package rows across 122 product lines (Container bci/openjdk, Container bci/openjdk-devel, … (122 product lines)): Fixed 694, Known Not Affected 49. https://www.suse.com/security/cve/CVE-2018-18500/
ubuntu medium CVE-2018-18500 medium priority: Ubuntu including 5 source packages (firefox, mozjs38, mozjs52, mozjs60, thunderbird), 80 status rows across 16 suites (bionic, cosmic, disco, eoan, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, trusty, upstream, xenial): DNE 35, released 32, ignored 13. https://ubuntu.com/security/CVE-2018-18500

Affected software / configurations for CVE-2018-18500

Vendor Product Version Raw CPE
mozilla firefox < 65.0 cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
mozilla firefox_esr < 60.5 cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*
mozilla thunderbird < 60.5 cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
canonical ubuntu_linux 14.04 cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:*
canonical ubuntu_linux 16.04 cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*
canonical ubuntu_linux 18.04 cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
canonical ubuntu_linux 18.10 cpe:2.3:o:canonical:ubuntu_linux:18.10:*:*:*:*:*:*:*
debian debian_linux 8.0 cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
redhat enterprise_linux_desktop 6.0 cpe:2.3:o:redhat:enterprise_linux_desktop:6.0:*:*:*:*:*:*:*
redhat enterprise_linux_desktop 7.0 cpe:2.3:o:redhat:enterprise_linux_desktop:7.0:*:*:*:*:*:*:*
redhat enterprise_linux_server 6.0 cpe:2.3:o:redhat:enterprise_linux_server:6.0:*:*:*:*:*:*:*
redhat enterprise_linux_server 7.0 cpe:2.3:o:redhat:enterprise_linux_server:7.0:*:*:*:*:*:*:*
redhat enterprise_linux_server_aus 7.6 cpe:2.3:o:redhat:enterprise_linux_server_aus:7.6:*:*:*:*:*:*:*
redhat enterprise_linux_server_eus 7.6 cpe:2.3:o:redhat:enterprise_linux_server_eus:7.6:*:*:*:*:*:*:*
redhat enterprise_linux_server_tus 7.6 cpe:2.3:o:redhat:enterprise_linux_server_tus:7.6:*:*:*:*:*:*:*
redhat enterprise_linux_workstation 6.0 cpe:2.3:o:redhat:enterprise_linux_workstation:6.0:*:*:*:*:*:*:*
redhat enterprise_linux_workstation 7.0 cpe:2.3:o:redhat:enterprise_linux_workstation:7.0:*:*:*:*:*:*:*

References for CVE-2018-18500

URL Tags
http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00021.html
http://www.securityfocus.com/bid/106781 Third Party Advisory VDB Entry
https://access.redhat.com/errata/RHSA-2019:0218 Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:0219 Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:0269 Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:0270 Third Party Advisory
https://lists.debian.org/debian-lts-announce/2019/01/msg00025.html Mailing List Third Party Advisory
https://lists.debian.org/debian-lts-announce/2019/02/msg00024.html Mailing List Third Party Advisory
https://security.gentoo.org/glsa/201903-04 Third Party Advisory
https://security.gentoo.org/glsa/201904-07
https://usn.ubuntu.com/3874-1/ Third Party Advisory
https://usn.ubuntu.com/3897-1/ Third Party Advisory
https://www.debian.org/security/2019/dsa-4376 Third Party Advisory
https://www.debian.org/security/2019/dsa-4392 Third Party Advisory
https://www.mozilla.org/security/advisories/mfsa2019-01/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-02/ Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-03/ Vendor Advisory
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