CVE-2019-17026
HighExploitedPublic exploitIncorrect alias information in IonMonkey JIT compiler for setting array elements could lead to a type confusion.
Published Mar 2, 2020 · Updated Aug 4, 2026 · Also known as DEBIAN-CVE-2019-17026, DLA-2093-1, MFSA 2020-03, MFSA 2020-04, UBUNTU-CVE-2019-17026
Key Facts
Patch immediately- CVE-2019-17026 is a high-severity vulnerability (CVSS 8.8 v3.1) affecting Firefox (Mozilla), Thunderbird (Mozilla), Ubuntu Linux (Canonical) and 17 more products.
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Jan 7, 2020. Public exploit code is available.
- EPSS estimates a 46% probability of exploitation in the next 30 days.
- Fixed versions are available, including Firefox 0:68.4.1-1.el6_10, Firefox 0:68.4.1-1.el7_7, Firefox 0:68.4.1-1.el8_1.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
8.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
46%
Higher than 98.8% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2019-17026 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
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.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Nov 3, 2021 | May 3, 2022 | Not reported |
| Industry KEV feed | Jan 7, 2020 | May 3, 2022 | Not reported |
| CIRCL KEV | Nov 3, 2021 | May 3, 2022 | Not reported |
| ENISA EUVD | Nov 3, 2021 | n/a | Not reported |
Required action: Apply updates per vendor instructions.
Affected Products
192 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| FirefoxMozilla | >= unspecified | 72.0.1 |
| ThunderbirdMozilla | >= unspecified | 68.4.1 |
| Ubuntu LinuxCanonical | 16.04 | n/a |
| Firefox ESRalpine | >= unspecified | 68.4.1-r0 |
| librewolfalpine | See advisory | 71.0.1-r0 |
Patched Releases
Firefox
0:68.4.1-1.el6_10, 0:68.4.1-1.el7_7, 0:68.4.1-1.el8_1, 68.4.1-1.0.1.el6_10, 68.4.1-1.0.1.el7_7, 68.4.1-1.0.1.el8_1, 71.0.1-r0, 72.0.1-1, 72.0.1+build1-0ubuntu0.16.04.1, 72.0.1+build1-0ubuntu0.18.04.1, 72.0.1+build1-0ubuntu1, 72.0.1, 68.4.1
Firefox ESR
68.4.1, 128.5.1-1.1, 68.4.1-r0, 68.4.1esr-1, 68.4.1esr-1~deb10u1, 68.4.1esr-1~deb8u1, 68.4.1esr-1~deb9u1
firefox-esr-branding-upstream
128.5.1-1.1
firefox-esr-translations-common
128.5.1-1.1
firefox-esr-translations-other
128.5.1-1.1
librewolf
71.0.1-r0
Thunderbird
68.4.1, 0:68.4.1-2.el6_10, 0:68.4.1-2.el7_7, 0:68.4.1-2.el8_1, 1:68.4.1-1, 1:68.4.1-1~deb10u1, 1:68.4.1-1~deb8u1, 1:68.4.1-1~deb9u1, 1:68.4.1+build1-0ubuntu0.18.04.1, 1:68.4.1+build1-0ubuntu1, 1:68.7.0+build1-0ubuntu0.16.04.2, 68.4.1-1, 68.4.1-2.0.1.el6_10, 68.4.1-2.0.1.el7_7, 68.4.1-2.0.1.el8_1, 68.4.1-2.amzn2.0.1
MozillaFirefox
68.4.1-109.101.1, 68.4.1-3.66.1, 68.4.1-78.57.1, 68.4.1-lp151.2.24.1, 92.0-1.2
MozillaFirefox-branding-upstream
68.4.1-lp151.2.24.1, 92.0-1.2
MozillaFirefox-buildsymbols
68.4.1-lp151.2.24.1
MozillaFirefox-devel
68.4.1-109.101.1, 68.4.1-3.66.1, 68.4.1-lp151.2.24.1, 92.0-1.2
MozillaFirefox-translations-common
68.4.1-109.101.1, 68.4.1-3.66.1, 68.4.1-78.57.1, 68.4.1-lp151.2.24.1, 92.0-1.2
MozillaFirefox-translations-other
68.4.1-3.66.1, 68.4.1-78.57.1, 68.4.1-lp151.2.24.1, 92.0-1.2
MozillaThunderbird
68.4.1-3.66.1, 68.4.1-lp151.2.22.2, 91.1.1-1.1
MozillaThunderbird-translations-common
68.4.1-3.66.1, 68.4.1-lp151.2.22.2, 91.1.1-1.1
MozillaThunderbird-translations-other
68.4.1-3.66.1, 68.4.1-lp151.2.22.2, 91.1.1-1.1
mozjs60
60.9.0-3.ph3
Timeline
Added to Industry KEV feed
Jan 7, 2020
Publicly disclosed
Mar 2, 2020
Added to CISA KEV
Nov 3, 2021
Added to CIRCL KEV
Nov 3, 2021
Added to ENISA EUVD
Nov 3, 2021
Last updated
Aug 4, 2026
Weakness Type
- CWE-843 Access of Resource Using Incompatible Type ('Type Confusion')
References
- advisoryRHSA-2020:0085
- advisoryRHSA-2020:0086
- advisoryRHSA-2020:0111
- advisoryRHSA-2020:0120
- advisoryRHSA-2020:0123
FAQ
Common Questions.
Incorrect alias information in IonMonkey JIT compiler for setting array elements could lead to a type confusion.
Affected: Firefox (Mozilla) versions >= unspecified; Thunderbird (Mozilla) versions >= unspecified; Ubuntu Linux (Canonical) versions 16.04, among others. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Jan 7, 2020.
Yes. It was added on Nov 3, 2021 with a federal remediation due date of May 3, 2022.
Public exploit code is available.
Fixed versions are available, including Firefox 0:68.4.1-1.el6_10, Firefox 0:68.4.1-1.el7_7, Firefox 0:68.4.1-1.el8_1.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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