CVE-2025-0239 - CVE House
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Status published Unknown CVE-2025-0239

Alt-Svc ALPN validation failure when redirected

Vulnerability Description

When using Alt-Svc, ALPN did not properly validate certificates when the original server is redirecting to an insecure site. This vulnerability was fixed in Firefox 134, Firefox ESR 128.6, Thunderbird 134, and Thunderbird 128.6.

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

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Credits & Attribution

The following person or organization is credited with identifying this vulnerability, as recorded in the NVD database:

  • Paul Gerste

References

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Affected Vendor

Affected Software

Firefox, Thunderbird
Vulnerable Versions:
128.6, 134

Timeline

Official Publish: January 7th, 2025
Last Modified: April 13th, 2026
Added to House: July 22nd, 2026

CVSS Vectors

No vector data available

Weaknesses (CWE)

No CWE data available

MITRE ATT&CK TTPs

No associated TTPs found for this vulnerability.