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CVE-2018-5099

29
FAUCET Score

CVE-2018-5099 is a critical use-after-free vulnerability affecting Mozilla Firefox, Firefox ESR, and Thunderbird versions prior to 58 and 52.6 respectively. This flaw allows for a potentially exploitable crash due to strong references to freed browser objects, carrying a CVSS score of 9.8 (CRITICAL) with a network attack vector, low complexity, and high impact on confidentiality, integrity, and availability. While highly severe, there is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
7.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:7.0:*:*:*:*:*:*:*
8.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
9.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
6.0CPE matchmatch criteria
cpe:2.3:o:redhat:enterprise_linux_desktop:6.0:*:*:*:*:*:*:*
7.0CPE matchmatch criteria
cpe:2.3:o:redhat:enterprise_linux_desktop:7.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

9.8CRITICAL

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.0

Exploit Intelligence

EPSS Score
3.07%
Probability of exploitation in next 30 days
EPSS Percentile
86.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0307 is in the 78th percentile among its peer group of 36,897 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (5)

redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: firefox-0:52.6.0-1.el6_9
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: thunderbird-0:52.6.0-1.el6_9
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: firefox-0:52.6.0-1.el7_4
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: thunderbird-0:52.6.0-1.el7_4
View patch
mozillavendor investigatingvia nvd_reference
View patch

Vendor Advisories (1)

redhatCVE-2018-5099Important

Mozilla: Use-after-free with widget listener (MFSA 2018-03)

Jan 23, 2018

References

access.redhat.com / errata/RHSA-2018:0122
Third Party Advisory
access.redhat.com / errata/RHSA-2018:0262
Third Party Advisory
bugzilla.mozilla.org / show_bug.cgi
Issue TrackingPermissions RequiredThird Party Advisory
lists.debian.org / debian-lts-announce/2018/01/msg00030.html
Third Party Advisory
lists.debian.org / debian-lts-announce/2018/01/msg00036.html
Third Party Advisory
usn.ubuntu.com / 3544-1
Third Party Advisory
debian.org / security/2018/dsa-4096
Third Party Advisory
debian.org / security/2018/dsa-4102
Third Party Advisory
mozilla.org / security/advisories/mfsa2018-02
Vendor Advisory
mozilla.org / security/advisories/mfsa2018-03
Vendor Advisory
mozilla.org / security/advisories/mfsa2018-04
Vendor Advisory
securityfocus.com / bid/102783
Third Party AdvisoryVDB Entry
securitytracker.com / id/1040270
Third Party AdvisoryVDB Entry