CVE-2019-17017Public exploitNetwork attack vector

Browser crash via BigInt-object type confusion

Published Jan 8, 2020 · Updated Aug 5, 2024

Type confusion in Mozilla Firefox before 72 and Firefox ESR before 68.4 allows remote attackers to crash the browser via web content. XPCVariant.cpp's array homogenizer omits BigInt handling, treats a BigInt value as an object, and dereferences it when XSLTProcessor.setParameter supplies a crafted array. A user must load attacker-controlled content; Mozilla states that sufficient effort can extend the crash to arbitrary code execution.

CVSS severity8.8
High
EPSS probability2.49%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Type confusion in Mozilla Firefox before 72 and Firefox ESR before 68.4 allows remote attackers to crash the browser via web content. XPCVariant.cpp's array homogenizer omits BigInt handling, treats a BigInt value as an object, and dereferences it when XSLTProcessor.setParameter supplies a crafted array. A user must load attacker-controlled content; Mozilla states that sufficient effort can extend the crash to arbitrary code execution.

The record

CVE
CVE-2019-17017
Published
Jan 8, 2020
Updated
Aug 5, 2024
Vendor
Mozilla
Product
Firefox
Classifications
CWE-843, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 8, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=before 72

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=before 72
Mozilla · Firefox ESRversion=before 68.4

Published CVSS scores

8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-843Access of Resource Using Incompatible Type ('Type Confusion')
T1203Exploitation for Client Execution

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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