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ExploitedIn CISA KEVFix available

CVE-2019-17026

Exploitation confirmed. First attested on 2021-11-03 by CISA-ADP, CISA KEV, GCVE · kevintel.

  • Published2020-03-02
  • Fixed in72.0.1 · 68.4.1
  • WeaknessCWE-843

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2020-03-0205:15CVE publishedNVD
  2. 2021-05-13Exploit-DB entryExploit-DB
  3. 2021-11-03Added to the CISA KEV catalogCISA KEV
  4. 2021-11-03Listed as exploited by GCVEGCVE
  5. 2021-11-03Exploitation first reportedCISA KEV
  6. 2025-02-0712:48SSVC exploitation set to activeCISA-ADP

Observed activity

isMalicious corpus · updated 2026-11-04 03:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2019-17026?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2019-17026?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Mozilla firefox
BranchAffectedFixed in
72.0< 72.0.172.0.1
68.4< 68.4.168.4.1
Canonical ubuntu linux
BranchAffectedFixed in
16.4= 16.04no fix published
Mozilla thunderbird
BranchAffectedFixed in
68.4< 68.4.168.4.1

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA3 products

As mozilla, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • Mozilla Firefox ESR
    Affected
    • < 68.4.1fixed in 68.4.1custom
  • Mozilla Thunderbird
    Affected
    • < 68.4.1fixed in 68.4.1custom
  • Mozilla Firefox
    Affected
    • < 72.0.1fixed in 72.0.1custom

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2021-05-13

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • firefoxUbuntu:20.04:LTSall versions · fixed in 72.0.1+build1-0ubuntu1
  • firefoxUbuntu:18.04:LTSall versions · fixed in 72.0.1+build1-0ubuntu0.18.04.1
  • firefoxUbuntu:16.04:LTSall versions · fixed in 72.0.1+build1-0ubuntu0.16.04.1
  • firefoxRed Hat:rhel_e4s:8.0::appstreamall versions · fixed in 0:68.4.1-1.el8_0and 2 other packages
  • firefoxRed Hat:enterprise_linux:8::appstreamall versions · fixed in 0:68.4.1-1.el8_1and 2 other packages
  • firefoxRed Hat:enterprise_linux:7::workstationall versions · fixed in 0:68.4.1-1.el7_7and 1 other package
  • firefoxRed Hat:enterprise_linux:7::serverall versions · fixed in 0:68.4.1-1.el7_7and 1 other package
  • firefoxRed Hat:enterprise_linux:7::clientall versions · fixed in 0:68.4.1-1.el7_7and 1 other package

89 more package ranges on OSV.dev

Vendor advisories

  • CVE-2019-17026 Red Hat Product Security205 products fixed · 2 known affected

    Mozilla: IonMonkey type confusion with StoreElementHole and FallibleStoreElement

    firefox as a component of Red Hat Enterprise Linux 5 · thunderbird as a component of Red Hat Enterprise Linux 5

  • RHSA-2020:0295 Red Hat Product Security7 products fixed

    Red Hat Security Advisory: firefox security update

  • RHSA-2020:0292 Red Hat Product Security7 products fixed

    Red Hat Security Advisory: thunderbird security update

  • RHSA-2020:0127 Red Hat Product Security7 products fixed

    Red Hat Security Advisory: thunderbird security update

  • RHSA-2020:0120 Red Hat Product Security11 products fixed

    Red Hat Security Advisory: thunderbird security update

  • RHSA-2020:0123 Red Hat Product Security19 products fixed

    Red Hat Security Advisory: thunderbird security update

3 more advisories

Full record on NVD

Fix

  1. Update Mozilla firefox to 72.0.1 · 68.4.1
  2. CISA’s required action: Apply updates per vendor instructions.due 2022-05-03
  3. Vendor fix Red Hat Product Security RHSA-2020:0295 · 7 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 After installing the update, Firefox must be restarted for the changes to take effect.
  4. Vendor fix Red Hat Product Security RHSA-2020:0292 · 7 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 All running instances of Thunderbird must be restarted for the update to take effect.
  5. No fix planned, says the vendor Red Hat Product Security CVE-2019-17026 · 2 productsOut of support scope

Advisories and patches

Detection

read 2026-11-03 22:42 UTC
Nuclei template
none so far
ProjectDiscovery
Exploit-DB
EDB-49864
Exploit-DB
Proof-of-concept repositories
2 repositories, unverifiedmaxpl0it/CVE-2019-17026-Exploitlsw29475/CVE-2019-17026
PoC-in-GitHub
Metasploit modules
none listed
Metasploit Framework

CISA Known Exploited Vulnerability

Date Added
2021-11-03
Patch Due Date
2022-05-03
Ransomware Use
Unknown
Required Action
Apply updates per vendor instructions.

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Published
2020-03-02
Last Modified
2026-06-17
NVD status
Analyzed
GitHub Advisory
GHSA-9m3f-27xq-x4j5

Frequently asked questions

What is CVE-2019-17026?

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.

Is CVE-2019-17026 actively exploited?

Yes. CVE-2019-17026 is on the CISA Known Exploited Vulnerabilities (KEV) catalog, meaning it has been confirmed as actively exploited in the wild. CISA requires federal agencies to patch by 2022-05-03.

What is the CVSS score for CVE-2019-17026?

CVE-2019-17026 has a CVSS v3 base score of 8.8 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

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Sources for this record