CVE-2025-9901
CSIRTS triage
- What
- Improper handling of the HTTP Vary header in libsoup caching allows cache confusion or bypass.
- Who is affected
- Applications using libsoup for HTTP caching with malformed or malicious Vary headers.
- Urgency
- Medium priority with a CVSS score of 5.9; not yet exploited.
- Action
- Update libsoup to the patched version.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Low exploitation risk0.46% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 37% of all EPSS-scored CVEs.
Advisory coverage (1)
- mediumCVE-2025-9901: Libsoup: improper handling of http vary header in libsoup cachingmsrc · 2026-08-06
External references
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[](https://www.csirts.com/cve/CVE-2025-9901)