Vulnerability report

Exploited in the wild Confirmed confidence In CISA KEV

CVE-2019-17026

Firefox ESR

Mozilla / Firefox ESR · affected before 68.4.1

Watch CVE-2019-17026 Browse KEV feed
Severity
CVSS 8.8 · High
Confidence
Confirmed
Exploit status
Exploited in the wild
EPSS
46.3%
First observed
—
Last observed
—

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2019-17026 is an unauthenticated vulnerability affecting Mozilla Firefox ESR and 2 other products. Incorrect alias information in IonMonkey JIT compiler for setting array elements could lead to a type confusion....

Is it exploited?

Yes. Previdian tracks this CVE as a known exploited vulnerability. Confidence is confirmed. Listed in CISA KEV.

Who is affected?

Mozilla / Firefox ESR affected before 68.4.1.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

Incorrect alias information in IonMonkey JIT compiler for setting array elements could lead to a type confusion

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.

Mozilla Affected
Firefox ESR
Before 68.4.1
Mozilla Affected
Thunderbird
Before 68.4.1
Mozilla Affected
Firefox
Before 72.0.1
View vendor advisory (opens in new tab)
Published
02 Mar 2020
Exploitation Reported
03 Nov 2021
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
Required

Tags

cisa

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

CISA

Recorded 03 Nov 2021

A trusted third party reported exploitation.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

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Source Added
CISA First 2021-11-03 00:00 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
0
0
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

No detection artifacts or sensor request patterns are available for this CVE yet.

Check back as sensor telemetry and scanner integrations are updated.

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

8.8 High

Potential damage if exploited. Separate from whether attackers are using it.

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

EPSS

46.3%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Access of Resource Using Incompatible Type ('Type Confusion') CWE-843

All CVSS Scores

CVSS v3.1 8.8 High

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS v2.0 6.8 Medium

AV:N/AC:M/Au:N/C:P/I:P/A:P

Timeline

From disclosure to observed exploitation

  1. 00:00 UTC

    Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  2. 04:05 UTC

    CVE published

    Vulnerability disclosed publicly

  3. 00:00 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2019-17026

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2019-17026",
  "confidence": "Confirmed",
  "cvss_score": 8.8,
  "cvss_estimated": false,
  "epss_score": 0.46311,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}