CVE-2019-17026

HIGH
8.8
CVSS Score
Published: March 2, 2020 at 04:05 AM UTC
Updated: June 17, 2026 at 02:23 AM UTC
4 products affected across 2 vendorsUbuntu LinuxFirefoxThunderbird

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Severity
HIGH8.8
Exploitation
CISA KEV
Exploit prediction
EPSS 46%
SSVC
Active

Actively Exploited

CISA Known Exploited Vulnerabilities (KEV) Catalog

EPSS Score46.3%

EPSS (Exploit Prediction Scoring System) estimates a 46.3% chance this CVE is exploited in the wild within the next 30 days — higher than 99% of all CVEs. It complements CVSS: a high EPSS on a mid-severity CVE can still be urgent.

Mozilla Firefox and Thunderbird contain a type confusion vulnerability due to incorrect alias information in the IonMonkey JIT compiler when setting array elements.

Required Action
Apply updates per vendor instructions.
Ransomware Use
Unknown
Added to KEV
Nov 3, 2021
Remediation Due
May 3, 2022
1639 days overdue

Description

Incorrect alias information in IonMonkey JIT compiler for setting array elements could lead to a type confusion. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Firefox ESR < 68.4.1, Thunderbird < 68.4.1, and Firefox < 72.0.1.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 68.4.1v < 72.0.1
Affected range stops below 68.4.1, so it looks safe — our inference, not a vendor statement
Affected range stops below 72.0.1, so it looks safe — our inference, not a vendor statement
v < 68.4.1
Affected range stops below 68.4.1, so it looks safe — our inference, not a vendor statement
v < 68.4.1
Affected range stops below 68.4.1, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (7)

Vendor Advisoryx_refsource_GENTOOThird Party Advisory
https://security.gentoo.org/glsa/202003-02
Vendor Advisoryx_refsource_UBUNTUThird Party Advisory
https://usn.ubuntu.com/4335-1/
US Government Resource
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-17026

SSVC — Action Prioritization

SSVCActiveNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.8HIGHCISA-ADP
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-843

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