CVE-2026-109705: Sandbox escape, site isolation issue due to incorrect boundary conditions, use-after-free in the Networking component

Published Oct 13, 2026
·
Updated

Sandbox escape, site isolation issue due to incorrect boundary conditions, use-after-free in the Networking component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, Thunderbird 153.5, and Firefox ESR 115.44.

Other sources

Sandbox escape, site isolation issue due to incorrect boundary conditions, use-after-free in the Networking component. This vulnerability was fixed in Firefox 158 and Firefox ESR 153.5.

— Red Hat

Affected Software

18 affected componentsFixes available
Mozilla Thunderbird<153.5
153.5
Mozilla Firefox ESR<115.44
115.44
ubuntu/mozjs52*
ubuntu/mozjs38*
ubuntu/mozjs68*
ubuntu/mozjs52*
ubuntu/mozjs102*
ubuntu/mozjs78*
ubuntu/mozjs91*
ubuntu/thunderbird*
ubuntu/mozjs102*
ubuntu/mozjs115*
Mozilla Firefox<158
158
Mozilla Firefox ESR<153.5
153.5
Mozilla Thunderbird<158
158
debian/firefox
159.0-1
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
debian/thunderbird<=1:140.12.0esr-1~deb12u1, <=1:140.12.0esr-1~deb13u1
1:153.6.0esr-1~deb12u21:153.6.0esr-1~deb13u11:153.5.0esr-11:153.6.0esr-1

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

    Fixed in 115.44
  3. Upgrade

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

    Fixed in 158
  4. Upgrade

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

    Fixed in 159.0-1
  5. 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
  6. Upgrade

    Upgrade debian/thunderbird to a version that resolves this vulnerability.

    Fixed in 1:153.6.0esr-1~deb12u2Fixed in 1:153.6.0esr-1~deb13u1Fixed in 1:153.5.0esr-1Fixed in 1:153.6.0esr-1
  7. Upgrade

    Upgrade Firefox to a version that resolves this vulnerability.

    Fixed in 158
  8. Upgrade

    Upgrade Firefox ESR to a version that resolves this vulnerability.

    Fixed in 153.5
  9. Upgrade

    Upgrade Thunderbird to a version that resolves this vulnerability.

    Fixed in 158
  10. Upgrade

    Upgrade Thunderbird to a version that resolves this vulnerability.

    Fixed in 153.5
  11. Upgrade

    Upgrade Firefox ESR to a version that resolves this vulnerability.

    Fixed in 115.44

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·12:57 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 releases include the fix?

The vulnerability was fixed in Firefox 158 and Firefox ESR 153.5.

2

Does exploitation require authentication or prior local access?

The CVSS vector indicates network attackability with low attack complexity and no privileges required. It also indicates user interaction is required.

3

What security impact could successful exploitation have?

The CVSS vector rates impacts to confidentiality, integrity, and availability as high, with scope changed. The issue involves a sandbox escape and site-isolation weakness in the Networking component.

Company

Resources

Contact

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