// For flags

CVE-2025-6425

firefox: thunderbird: The WebCompat WebExtension shipped with Firefox exposed a persistent UUID

Severity Score

4.3
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

Track
*SSVC
Descriptions

An attacker who enumerated resources from the WebCompat extension could have obtained a persistent UUID that identified the browser, and persisted between containers and normal/private browsing mode, but not profiles. This vulnerability affects Firefox < 140, Firefox ESR < 115.25, and Firefox ESR < 128.12.

An attacker who enumerated resources from the WebCompat extension could have obtained a persistent UUID that identified the browser, and persisted between containers and normal/private browsing mode, but not profiles. This vulnerability affects Firefox < 140, Firefox ESR < 115.25, Firefox ESR < 128.12, Thunderbird < 140, and Thunderbird < 128.12.

A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the following issue: An attacker who enumerated resources from the WebCompat extension could have obtained a persistent UUID that identified the browser and persisted between containers and normal/private browsing mode but not profiles.

This update for MozillaFirefox fixes the following issues. Use-after-free in FontFaceSet The WebCompat WebExtension shipped with Firefox exposed a persistent UUID No warning when opening executable terminal files on macOS Incorrect parsing of URLs could have allowed embedding of youtube.com Content-Disposition header ignored when a file is included in an embed or object tag.

*Credits: Rob Wu
CVSS Scores
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None
Attack Vector
Network
Attack Complexity
Low
Authentication
None
Confidentiality
Partial
Integrity
Partial
Availability
None
* Common Vulnerability Scoring System
SSVC
  • Decision:Track
Exploitation
None
Automatable
No
Tech. Impact
Partial
* Organization's Worst-case Scenario
Timeline
  • 2025-06-20 CVE Reserved
  • 2025-06-24 CVE Published
  • 2025-07-03 CVE Updated
  • 2025-07-03 EPSS Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-200: Exposure of Sensitive Information to an Unauthorized Actor
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Mozilla
Search vendor "Mozilla"
Firefox
Search vendor "Mozilla" for product "Firefox"
*-
Affected
Mozilla
Search vendor "Mozilla"
Firefox Esr
Search vendor "Mozilla" for product "Firefox Esr"
*-
Affected
Mozilla
Search vendor "Mozilla"
Thunderbird
Search vendor "Mozilla" for product "Thunderbird"
*-
Affected
Oracle
Search vendor "Oracle"
Linux
Search vendor "Oracle" for product "Linux"
*-
Affected
Redhat
Search vendor "Redhat"
Enterprise Linux
Search vendor "Redhat" for product "Enterprise Linux"
*-
Affected
Redhat
Search vendor "Redhat"
Rhel Aus
Search vendor "Redhat" for product "Rhel Aus"
*-
Affected
Redhat
Search vendor "Redhat"
Rhel E4s
Search vendor "Redhat" for product "Rhel E4s"
*-
Affected
Redhat
Search vendor "Redhat"
Rhel Eus
Search vendor "Redhat" for product "Rhel Eus"
*-
Affected
Redhat
Search vendor "Redhat"
Rhel Tus
Search vendor "Redhat" for product "Rhel Tus"
*-
Affected
Alma
Search vendor "Alma"
Linux
Search vendor "Alma" for product "Linux"
*-
Affected
Debian
Search vendor "Debian"
Debian Linux
Search vendor "Debian" for product "Debian Linux"
*-
Affected
Fedoraproject
Search vendor "Fedoraproject"
Fedora
Search vendor "Fedoraproject" for product "Fedora"
*-
Affected
Freebsd
Search vendor "Freebsd"
Freebsd
Search vendor "Freebsd" for product "Freebsd"
*-
Affected
Opensuse
Search vendor "Opensuse"
Leap
Search vendor "Opensuse" for product "Leap"
*-
Affected
Oracle
Search vendor "Oracle"
Linux
Search vendor "Oracle" for product "Linux"
*-
Affected
Redhat
Search vendor "Redhat"
Enterprise Linux
Search vendor "Redhat" for product "Enterprise Linux"
*-
Affected
Redhat
Search vendor "Redhat"
Rhel Aus
Search vendor "Redhat" for product "Rhel Aus"
*-
Affected
Redhat
Search vendor "Redhat"
Rhel E4s
Search vendor "Redhat" for product "Rhel E4s"
*-
Affected
Redhat
Search vendor "Redhat"
Rhel Els
Search vendor "Redhat" for product "Rhel Els"
*-
Affected
Redhat
Search vendor "Redhat"
Rhel Eus
Search vendor "Redhat" for product "Rhel Eus"
*-
Affected
Redhat
Search vendor "Redhat"
Rhel Tus
Search vendor "Redhat" for product "Rhel Tus"
*-
Affected
Slackware
Search vendor "Slackware"
Slackware Linux
Search vendor "Slackware" for product "Slackware Linux"
*-
Affected
Suse
Search vendor "Suse"
Sle-module-desktop-applications
Search vendor "Suse" for product "Sle-module-desktop-applications"
*-
Affected
Suse
Search vendor "Suse"
Sle Hpc-espos
Search vendor "Suse" for product "Sle Hpc-espos"
*-
Affected
Suse
Search vendor "Suse"
Sle Hpc-ltss
Search vendor "Suse" for product "Sle Hpc-ltss"
*-
Affected
Suse
Search vendor "Suse"
Sle Hpc
Search vendor "Suse" for product "Sle Hpc"
*-
Affected
Suse
Search vendor "Suse"
Sled
Search vendor "Suse" for product "Sled"
*-
Affected
Suse
Search vendor "Suse"
Sles-ltss-extended-security
Search vendor "Suse" for product "Sles-ltss-extended-security"
*-
Affected
Suse
Search vendor "Suse"
Sles-ltss
Search vendor "Suse" for product "Sles-ltss"
*-
Affected
Suse
Search vendor "Suse"
Sles
Search vendor "Suse" for product "Sles"
*-
Affected
Suse
Search vendor "Suse"
Sles Sap
Search vendor "Suse" for product "Sles Sap"
*-
Affected