CVE-2025-5271: Vulnerability in Mozilla Firefox
Previewing a response in Devtools ignored CSP headers, which could have allowed content injection attacks. This vulnerability was fixed in Firefox 139 and Thunderbird 139.
AI Analysis
Technical Summary
The vulnerability CVE-2025-5271 affects Mozilla Firefox's Devtools preview functionality, which failed to enforce CSP headers when previewing responses. This could have allowed an attacker to inject content by bypassing CSP protections. The issue was addressed and fixed in Firefox 139. The CVSS 3.1 base score is 6.5, reflecting a network attack vector with low complexity, no privileges or user interaction required, and impacts on confidentiality and integrity but not availability.
Potential Impact
If unpatched, this vulnerability could allow content injection attacks via the Devtools preview feature by ignoring CSP headers, potentially leading to unauthorized content being rendered or executed. However, the impact is limited to the Devtools context and is rated as medium severity. There are no reports of exploitation in the wild.
Mitigation Recommendations
This vulnerability is fixed in Mozilla Firefox version 139. Users and administrators should update to Firefox 139 or later to remediate this issue. No additional mitigation steps are required as the vendor advisory confirms the official fix is available.
CVE-2025-5271: Vulnerability in Mozilla Firefox
Description
Previewing a response in Devtools ignored CSP headers, which could have allowed content injection attacks. This vulnerability was fixed in Firefox 139 and Thunderbird 139.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability CVE-2025-5271 affects Mozilla Firefox's Devtools preview functionality, which failed to enforce CSP headers when previewing responses. This could have allowed an attacker to inject content by bypassing CSP protections. The issue was addressed and fixed in Firefox 139. The CVSS 3.1 base score is 6.5, reflecting a network attack vector with low complexity, no privileges or user interaction required, and impacts on confidentiality and integrity but not availability.
Potential Impact
If unpatched, this vulnerability could allow content injection attacks via the Devtools preview feature by ignoring CSP headers, potentially leading to unauthorized content being rendered or executed. However, the impact is limited to the Devtools context and is rated as medium severity. There are no reports of exploitation in the wild.
Mitigation Recommendations
This vulnerability is fixed in Mozilla Firefox version 139. Users and administrators should update to Firefox 139 or later to remediate this issue. No additional mitigation steps are required as the vendor advisory confirms the official fix is available.
Technical Details
- Data Version
- 5.1
- Assigner Short Name
- mozilla
- Date Reserved
- 2025-05-27T12:29:29.015Z
- Cvss Version
- null
- State
- PUBLISHED
Threat ID: 6835b383182aa0cae2110b01
Added to database: 5/27/2025, 12:43:47 PM
Last enriched: 4/14/2026, 11:50:26 AM
Last updated: 5/8/2026, 12:16:22 PM
Views: 103
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