Vulnerability · CVE-2025-5271
Previewing a response in Devtools ignored CSP headers, which could have allowed content injection attacks.
Published May 27, 2025 · corrected/updated Apr 13, 2026 · mozilla · evidence confidence high
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.
Grounded briefings
Catalog interpretations for three audiences. Each brief cites ingested metadata and the original advisories below. They are not independent research and they do not invent exploit steps.
Executive
CVE-2025-5271 is a medium public vulnerability record for mozilla. It is not currently listed in the CISA Known Exploited catalog. Check the linked vendor or CERT advisories for patch status. This summary is a catalog interpretation of the ingested metadata and cites the original advisories below.
System administrator
Identify whether mozilla is in your estate, then compare installed versions with the affected ranges. Affected packages or ranges on record: mozilla. Check the linked vendor or CERT advisories for patch status. Prefer the vendor or distribution advisory linked in Sources before changing production systems. This is a catalog interpretation, not a runbook.
Security analyst
Signals on file: CVSS 6.5 (technical impact); EPSS 0.3% (30-day exploitation probability). It is not currently listed in the CISA Known Exploited catalog. Sources contributing to this record: epss, euvd. Public exploit references, when present, are outbound links only and are not proof of active exploitation. This is a catalog interpretation of stored metadata.
Exploitation and remediation
Exploitation evidence
Not listed as known exploited in CISA KEV. Not in CISA KEV or VulnCheck KEV.
Patch and remediation
A patch or advisory reference is linked. Open the original publisher for availability by product version.
Safe detection guidance
Compare installed versions with the affected ranges below and verify the advisory from the original publisher. This site stores metadata and outbound links only; it does not ship exploit code or proof-of-concept payloads.
Code
The project this record applies to. Exploit listings stay in References.
No public source repository is identified for this product.
Timeline
Detection, updates, and resolution for this record.
May 27, 2025 · EUVD
Detected
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.
Apr 13, 2026 · EUVD
Updated
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.
Affected
- vendor mozillaversion unspecified
Sources
- FIRST EPSSExploitation probabilityCVE-2025-5271
30-day exploitation probability 0.3%
first.org - EUVDVulnerability recordEUVD-2025-18105
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.
euvd.enisa.europa.eu