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CVE-2019-9813

43
FAUCET Score

CVE-2019-9813 is a high-severity type confusion vulnerability in the IonMonkey JIT compiler affecting Mozilla Firefox, Firefox ESR, and Thunderbird versions prior to 66.0.1 and 60.6.1 respectively. This flaw stems from incorrect handling of __proto__ mutations, which can lead to arbitrary memory read and write capabilities. With a CVSS score of 8.8 (HIGH) and an EPSS score indicating a higher exploitability probability than 97.8% of all CVEs, this vulnerability presents a significant risk. While not listed on CISA's KEV catalog, public exploit code exists on ExploitDB, and it has garnered community discussion, including a Reddit post detailing its use in Pwn2Own.

Impacted Technologies

VendorProductVersion(s)CPE
< 60.6.1CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
< 66.0.1CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
< 60.6.1CPE matchmatch criteria
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

8.8HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
5.9
CvssVersion
3.0

Exploit Intelligence

EPSS Score
7.39%
Probability of exploitation in next 30 days
EPSS Percentile
93.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
ExploitDB: EDB-46646 · Apr 3, 2019
This CVE's current EPSS score of 0.0739 is in the 94th percentile among its peer group of 14,855 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.2 Bluesky, 0.1 Mastodon, and 0.2 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 0.1 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (7)

redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: firefox-0:60.6.1-1.el7_6
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: firefox-0:60.6.1-1.el6_10
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: thunderbird-0:60.6.1-1.el6_10
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: thunderbird-0:60.6.1-1.el8
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: thunderbird-0:60.6.1-1.el7_6
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: firefox-0:60.6.1-1.el8
View patch
mozillavendor investigatingvia nvd_reference
View patch

Vendor Advisories (1)

redhatCVE-2019-9813Critical

Mozilla: Ionmonkey type confusion with __proto__ mutations

Mar 22, 2019

References

access.redhat.com / errata/RHSA-2019:0966
access.redhat.com / errata/RHSA-2019:1144
bugzilla.mozilla.org / show_bug.cgi
Issue TrackingPermissions RequiredVendor Advisory
mozilla.org / security/advisories/mfsa2019-09
Vendor Advisory
mozilla.org / security/advisories/mfsa2019-10
Vendor Advisory
mozilla.org / security/advisories/mfsa2019-12
Vendor Advisory