CVE-2025-6435: Vulnerability in Mozilla Firefox
If a user saved a response from the Network tab in Devtools using the Save As context menu option, that file may not have been saved with the `.download` file extension. This could have led to the user inadvertently running a malicious executable. This vulnerability was fixed in Firefox 140 and Thunderbird 140.
AI Analysis
Technical Summary
This vulnerability in Mozilla Firefox relates to improper sanitization of file extensions when saving responses from the Network tab in Devtools using the Save As option. Specifically, files may be saved without the .download extension, which is intended to prevent accidental execution of downloaded files. Without this extension, a malicious executable could be run inadvertently by the user. The issue was fixed in Firefox 140. The CVSS 3.1 base score is 8.1, indicating high severity with network attack vector, high impact on confidentiality, integrity, and availability, and no user interaction required.
Potential Impact
If exploited, this vulnerability could allow an attacker to trick a user into running a malicious executable file saved from the Network tab in Devtools. This could lead to arbitrary code execution with the privileges of the user running Firefox. The impact is high as it affects confidentiality, integrity, and availability. However, there are no known exploits in the wild as of the advisory date.
Mitigation Recommendations
Mozilla has released an official fix for this vulnerability in Firefox 140. Users and administrators should update to Firefox 140 or later to remediate this issue. No additional mitigation steps are required beyond applying the official update.
CVE-2025-6435: Vulnerability in Mozilla Firefox
Description
If a user saved a response from the Network tab in Devtools using the Save As context menu option, that file may not have been saved with the `.download` file extension. This could have led to the user inadvertently running a malicious executable. This vulnerability was fixed in Firefox 140 and Thunderbird 140.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability in Mozilla Firefox relates to improper sanitization of file extensions when saving responses from the Network tab in Devtools using the Save As option. Specifically, files may be saved without the .download extension, which is intended to prevent accidental execution of downloaded files. Without this extension, a malicious executable could be run inadvertently by the user. The issue was fixed in Firefox 140. The CVSS 3.1 base score is 8.1, indicating high severity with network attack vector, high impact on confidentiality, integrity, and availability, and no user interaction required.
Potential Impact
If exploited, this vulnerability could allow an attacker to trick a user into running a malicious executable file saved from the Network tab in Devtools. This could lead to arbitrary code execution with the privileges of the user running Firefox. The impact is high as it affects confidentiality, integrity, and availability. However, there are no known exploits in the wild as of the advisory date.
Mitigation Recommendations
Mozilla has released an official fix for this vulnerability in Firefox 140. Users and administrators should update to Firefox 140 or later to remediate this issue. No additional mitigation steps are required beyond applying the official update.
Technical Details
- Data Version
- 5.1
- Assigner Short Name
- mozilla
- Date Reserved
- 2025-06-20T14:51:42.561Z
- Cvss Version
- null
- State
- PUBLISHED
Threat ID: 685aa0274dc24046c1dc5ac8
Added to database: 6/24/2025, 12:55:03 PM
Last enriched: 4/14/2026, 11:52:33 AM
Last updated: 5/9/2026, 12:38:33 AM
Views: 133
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