8.8

CVE-2019-17026: Mozilla Firefox And Thunderbird Type Confusion Vulnerability

CVSS: 8.8v3.1HighKEVAnalyzed
AliasesUBUNTU-CVE-2019-17026DEBIAN-CVE-2019-17026DLA-2093-1
Published 02-03-2020Last modified 21-10-2025
Open JSON

Vulnerability summary

CVE-2019-17026 is a high (CVSS 8.8) Type Confusion vulnerability in Mozilla Firefox and Thunderbird. It is known to be exploited: CISA lists it, first on 03-11-2021. EPSS estimates a 46.31% chance of exploitation in the next 30 days, higher than 98.8% of scored vulnerabilities. 2 public exploits are recorded.

Overall risk
85/100
0100
Critical · default modelHow is this calculated?
CVSS score
8.8/10
010
High · v3.1 (CVE.org)
EPSS score
46.31%
0%100%
High · 0.00 pp in 30 days
KEVListedCISA
RansomwareNone recordedNo known use recorded
Public exploits2reference, exploit-database

Advisory lineage

Upstream 0 · Downstream 25 · Related 12
DLA-2071-1DSA-4600-1DSA-4603-1MGASA-2020-0027MGASA-2020-0034OPENSUSE-SU-2020:0060-1

Timeline

  1. 02-03-2020
    PublishedVulnerability first disclosed.
  2. 03-11-2021
    Added to CISA KEVMozilla Firefox And Thunderbird Type Confusion Vulnerability
  3. 03-05-2022
    CISA remediation dueApply updates per vendor instructions.
  4. 21-10-2025
    Last modifiedVulnerability information updated.

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.

CVSS metrics

5 scores · 4 sources · 2 versions

EPSS trend

Probability

46.31%

Chance of exploitation in the next 30 days

Percentile

99%

Versus all other CVEs

30-day change

0.00 pp

From 46.31% on 19-09-2026

19-09-202619-10-2026
EPSS score
46.31%

Known exploited

Compare KEV catalogs
CISA KEVListed
Added
03-11-2021
Federal due date
03-05-2022

CISA required action

Apply updates per vendor instructions. nvd.nist.gov/vuln/detail/CVE-2019-17026

Public exploits

2 found
  • referenceUnverified

    Exploit Reference (packetstormsecurity.com)

    Maturity: unknown

  • exploit-databaselocalwindows_x86-64Unverified

    Firefox 72 IonMonkey - JIT Type Confusion

    Maturity: poc

Weaknesses

CWE · root cause

Affected systems

Ubuntu4 products
  • firefox< 72.0.1+build1-0ubuntu0.16.04.1 | < 72.0.1+build1-0ubuntu0.18.04.1 | < 72.0.1+build1-0ubuntu1
  • mozjs38All versions (No fix recorded)
  • mozjs52All versions (No fix recorded)
  • thunderbird< 1:68.7.0+build1-0ubuntu0.16.04.2 | < 1:68.4.1+build1-0ubuntu0.18.04.1 | < 1:68.4.1+build1-0ubuntu1
Mozilla3 products
Debian2 products
  • firefox-esr< 68.4.1esr-1 | < 68.4.1esr-1~deb8u1
  • thunderbird< 1:68.4.1-1
Canonical1 product

4 vendors · 10 products

References

16 links
Show all 16 references