What’s Vulnerable › Vulnerabilities

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

• Severity: medium (CVSS 5.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-09-03 · updated 2026-10-18
• Weakness: CWE-524

Description

A flaw was found in libsoup’s caching mechanism, SoupCache, where the HTTP Vary header is ignored when evaluating cached responses. This header ensures that responses vary appropriately based on request headers such as language or authentication. Without this check, cached content can be incorrectly reused across different requests, potentially exposing sensitive user information. While the issue is unlikely to affect everyday desktop use, it could result in confidentiality breaches in proxy or multi-user environments.

Affected products

• Red Hat Enterprise Linux 10: all versions
• Red Hat Enterprise Linux 7: all versions
• Red Hat Enterprise Linux 8: all versions
• Red Hat Enterprise Linux 9: all versions

References

• https://access.redhat.com/security/cve/CVE-2025-9901
• https://bugzilla.redhat.com/show_bug.cgi?id=2392790
• https://gitlab.gnome.org/GNOME/libsoup/-/issues/453

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