Libsoup: improper handling of http vary header in libsoup caching — CVE-2025-9901

Summary

Advisory CVE-2025-9901. Libsoup: improper handling of http vary header in libsoup caching Vendor: Microsoft. Source: MSRC. Threat: medium. CVSS 5.9. See the official advisory for details.

What to do

General, cautious steps (verify details in the official source):

• Review exposure and plan remediation based on risk and environment.
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

Read the official source

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