CVE-2019-17011Network attack vector

Client crash via antitracking DocShell race

Published Jan 8, 2020 · Updated Aug 5, 2024

Use-after-free in Mozilla Firefox before 71, Firefox ESR before 68.3, and Thunderbird before 68.3 allows remote attackers to crash the client. The antitracking notification path calls nsDocShell::GetDocument during SetOnstorage processing after a race has freed an event-listener object. Triggering requires browser-like content and user interaction; Thunderbird disables scripting during ordinary mail reading, limiting email exposure.

CVSS severity7.5
High
EPSS probability1.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Mozilla Firefox before 71, Firefox ESR before 68.3, and Thunderbird before 68.3 allows remote attackers to crash the client. The antitracking notification path calls nsDocShell::GetDocument during SetOnstorage processing after a race has freed an event-listener object. Triggering requires browser-like content and user interaction; Thunderbird disables scripting during ordinary mail reading, limiting email exposure.

The record

CVE
CVE-2019-17011
Published
Jan 8, 2020
Updated
Aug 5, 2024
Vendor
Mozilla
Product
Firefox
Classifications
CWE-362, 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 71

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=before 71
Mozilla · Thunderbirdversion=before 68.3
Mozilla · Firefox ESRversion=before 68.3

Published CVSS scores

5.1NIST NVDAV:N/AC:H/Au:N/C:P/I:P/A:P
7.5NIST NVDCVSS:3.1/AV:N/AC:H/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

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

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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