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CVE-2019-17026

90
FAUCET Score

CVE-2019-17026 is a critical type confusion vulnerability in the IonMonkey JIT compiler of Mozilla Firefox and Thunderbird, affecting versions prior to 72.0.1 and 68.4.1 respectively. This flaw carries a CVSS score of 8.8 (High) due to its network-based attack vector, low attack complexity, and high potential for confidentiality, integrity, and availability impacts. It is actively exploited in the wild, with exploit code publicly available and significant community discussion, including its use in sophisticated attack chains.

Impacted Technologies

VendorProductVersion(s)CPE
< 68.4.1CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
< 72.0.1CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*
< 68.4.1CPE matchmatch criteria
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
16.04CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.8HIGH

CVSS:3.1/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
3.1

Exploit Intelligence

EPSS Score
43.42%
Probability of exploitation in next 30 days
EPSS Percentile
98.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-24
Model: v2026.06.15
Added to KEV · Nov 3, 2021
ExploitDB: EDB-49864 · May 13, 2021
This CVE's current EPSS score of 0.4342 is in the 99th percentile among its peer group of 14,824 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

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 (9)

redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8.0 Update Services for SAP SolutionsFixed in: firefox-0:68.4.1-1.el8_0
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: firefox-0:68.4.1-1.el6_10
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: thunderbird-0:68.4.1-2.el6_10
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: firefox-0:68.4.1-1.el7_7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: thunderbird-0:68.4.1-2.el7_7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: firefox-0:68.4.1-1.el8_1
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: thunderbird-0:68.4.1-2.el8_1
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8.0 Update Services for SAP SolutionsFixed in: thunderbird-0:68.4.1-2.el8_0
View patch
mozillavendor investigatingvia nvd_reference
View patch

Vendor Advisories (1)

redhatCVE-2019-17026Critical

Mozilla: IonMonkey type confusion with StoreElementHole and FallibleStoreElement

Jan 8, 2020

References

cisa.gov / known-exploited-vulnerabilities-catalog
US Government Resource
packetstormsecurity.com / files/162568/Firefox-72-IonMonkey-JIT-Type-Confusion.html
ExploitThird Party AdvisoryVDB Entry
bugzilla.mozilla.org / show_bug.cgi
Issue Tracking
security.gentoo.org / glsa/202003-02
Third Party Advisory
usn.ubuntu.com / 4335-1
Third Party Advisory
mozilla.org / security/advisories/mfsa2020-03
Vendor Advisory
mozilla.org / security/advisories/mfsa2020-04
Vendor Advisory