CVE-2026-109769 Details
Description
Information disclosure in the Networking: Cache component. This vulnerability was fixed in Firefox 158 and Thunderbird 158.
A vulnerability allowing information disclosure has been identified in the Networking: Cache component of Mozilla Firefox and Thunderbird. This issue arises because the Shared Compression Dictionary cache is not properly partitioned by OriginAttributes, which include important privacy-related data. As a result, a third-party server can track cross-site browsing history by using the Available-Dictionary HTTP request header, thereby bypassing Firefox's Network State Partitioning. This vulnerability affects Firefox versions prior to 158 and Thunderbird versions prior to 158.
Users can update to Firefox 158 or Thunderbird 158, where this vulnerability has been fixed.
Metrics
CVSS 4.0 Severity and Vector Strings:
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Oct 13, 2026CISA-ADP
Assessed Oct 13, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://bugzilla.mozilla.org/show_bug.cgi?id=2050313 | [email protected] | ExploitIssue TrackingTechnical DescriptionVendor |
| https://www.mozilla.org/security/advisories/mfsa2026-106/ | [email protected] | AdvisoryBundleVendor |
| https://www.mozilla.org/security/advisories/mfsa2026-109/ | [email protected] | AdvisoryBundleVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-200 | Exposure of Sensitive Information to an Unauthorized Actor | CISA-ADP |
Affected Products
| Product | Versions |
|---|---|
| Mozilla Firefox | >= 154, < 158 |
CPE
Remediation
| |
| Mozilla Thunderbird | >= 154, < 158 |
CPE
Remediation
| |
Change History
3 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Oct 13, 2026 | CVE Modified | [email protected] |
| Oct 13, 2026 | CVE Modified | CISA-ADP |
| Oct 13, 2026 | New CVE Received | [email protected] |
Volerion