Reference page — cumulative record through Sunday, October 4, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2019-17026

CVE-2019-17026HIGH

Mozilla Firefox and Thunderbird

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   L   N   R  U  H  H  H    8.8   .4631   98.8   YES

AFFECTED
  Product      Versions       Fixed
  Firefox ESR  unspecified –  —
  Thunderbird  unspecified –  —
  Firefox      unspecified –  —

TIMELINE
  Sep 30  Reserved by mozilla
  Mar 2   Published (CNA: mozilla)
  Nov 3   Added to CISA KEV, remediation due 2022-05-03

CWE-843 · CNA: mozilla · CVSS v3.1 · 7 references · KEV due May 3, 2022

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.

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
September 30, 2019	Reserved	Reserved by mozilla
March 2, 2020	Published	Published (CNA: mozilla)
November 3, 2021	KEV ADDED	Added to CISA KEV, remediation due 2022-05-03

Affected

Affected products and packages — 3 rows
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
Mozilla	Firefox ESR	—	unspecified	—
Mozilla	Thunderbird	—	unspecified	—
Mozilla	Firefox	—	unspecified	—

Weaknesses

CWE-843

References (7)

http://packetstormsecurity.com/files/162568/Firefox-72-IonMonkey-JIT-Type-Confusion.html [x_refsource_MISC]
https://bugzilla.mozilla.org/show_bug.cgi?id=1607443 [x_refsource_MISC]
https://security.gentoo.org/glsa/202003-02 [vendor-advisory, x_refsource_GENTOO]
https://usn.ubuntu.com/4335-1/ [vendor-advisory, x_refsource_UBUNTU]
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-17026 [government-resource]
https://www.mozilla.org/security/advisories/mfsa2020-03/ [x_refsource_MISC]
https://www.mozilla.org/security/advisories/mfsa2020-04/ [x_refsource_MISC]

Authoritative record: CVE-2019-17026 at cve.org

Vendors: mozilla

Weaknesses: CWE-843

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2019-17026 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Sunday, October 4, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.