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Vulnerabilities

Vulnerability · CVE-2025-5271

Previewing a response in Devtools ignored CSP headers, which could have allowed content injection attacks.

Published May 27, 2025 · catalog updated Apr 13, 2026 · Previewing a response in

Check if you run it

No confirmed exploitation is on record for CVE-2025-5271. EPSS is 0.30%. Act only if a listed version of Previewing a response in is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Previewing a response in).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium6.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.30%
Remediation
Advisory link
Affected products
vendor mozilla

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor mozillaversion unspecified

How to fix CVE-2025-5271

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2025-5271. EPSS is 0.30%. Act only if a listed version of Previewing a response in is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.30%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

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.

  1. 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.

  2. 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.

Sources

  • CVE.orgVulnerability recordCVE-2025-5271

    Official CVE identifier

    cve.org
  • 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

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.