CVE-2025-5271 | BDVDB-2026-280358 Detail

MozillaFirefox

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.

Impact#

Per CVSS v3.1: confidentiality impact low, integrity impact low, availability impact none. Attack vector: network.

Weaknesses#

CWE-116 Improper Encoding or Escaping of Output

References#

Exploit#

No public exploit known

History#

Version 12025-05-27Record published in the CVE List.
Version 22026-04-13Most recent update recorded in the CVE List.

Published

Published: 2025-05-27
Last modified: 2026-04-13

Vendor information

Vendor: Mozilla
Product: Firefox

All Mozilla vulnerabilities

Score

6.5 Medium

EPSS

less than 1%, Very Low

Estimated chance of exploitation in the next 30 days. EPSS percentile: 23.4.

KEV

Not listed in the CISA Known Exploited Vulnerabilities catalog.

Impact

Not classified

Action

No specific action is recorded in the source data. Check the references for vendor guidance.

Affected Systems

Vulnerable
Not stated
Fixed
139

Scoring System

CVSS v4.0

Not available

CVSS v3.1

6.5 Medium

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Metric breakdown
Attack Vector	Network
Attack Complexity	Low
Privileges Required	None
User Interaction	None
Scope	Unchanged
Confidentiality	Low
Integrity	Low
Availability	None

CVSS v3.0

Not available

CVSS v2

Not available

Source: CVE List v5 (record); CISA KEV (kev, action); FIRST EPSS (epss).