CVE-2026-109783: Mitigation bypass in the File Handling component

Published Oct 13, 2026
·
Updated

Mitigation bypass in the File Handling component. This vulnerability was fixed in Firefox ESR 153.5 and Thunderbird 153.5.

Affected Software

13 affected componentsFixes available
Mozilla Thunderbird<153.5
153.5
ubuntu/mozjs52*
ubuntu/mozjs38*
ubuntu/mozjs68*
ubuntu/mozjs52*
ubuntu/mozjs102*
ubuntu/mozjs78*
ubuntu/mozjs91*
ubuntu/thunderbird*
ubuntu/mozjs102*
ubuntu/mozjs115*
debian/firefox-esr<=140.12.0esr-1~deb12u1, <=140.15.0esr-1~deb13u1
153.6.0esr-1~deb12u2153.6.0esr-1~deb13u1153.5.1esr-1153.6.0esr-1
Mozilla Firefox ESR<153.5
153.5

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 153.5
  2. Upgrade

    Upgrade debian/firefox-esr to a version that resolves this vulnerability.

    Fixed in 153.6.0esr-1~deb12u2Fixed in 153.6.0esr-1~deb13u1Fixed in 153.5.1esr-1Fixed in 153.6.0esr-1
  3. Upgrade

    Upgrade Firefox ESR to a version that resolves this vulnerability.

    Fixed in 153.5
  4. Upgrade

    Upgrade Thunderbird to a version that resolves this vulnerability.

    Fixed in 153.5

Event History

Oct 13, 2026
CVE Published
via Mozilla·12:00 AM
Data Sourced
via Mozilla·12:00 AM
DescriptionSeverityAffected Software
Data Sourced
via Ubuntu·12:00 AM
RemedyDescriptionSeverityAffected Software
CVE Published
via MITRE·12:29 PM
Data Sourced
via MITRE·12:29 PM
Description
Data Sourced
via Red Hat·12:53 PM
DescriptionSeverityAffected Software
Data Sourced
via OSV·01:17 PM
DescriptionSeverityAffected Software
Data Sourced
via NVD·01:17 PM
DescriptionSeverityWeakness

Parent advisories

This vulnerability appears in the following advisories.

Peer vulnerabilities

Found alongside the following vulnerabilities.

Frequently Asked Questions

1

Which Firefox ESR release includes the fix?

The vulnerability was fixed in Firefox ESR 153.5.

Company

Resources

Contact

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