What’s Vulnerable › Vulnerabilities

CVE-2025-4035: Libsoup: cookie domain validation bypass via uppercase characters in libsoup

• Severity: medium (CVSS 4.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-04-29 · updated 2026-06-30
• Weakness: CWE-178

Description

A flaw was found in libsoup. When handling cookies, libsoup clients mistakenly allow cookies to be set for public suffix domains if the domain contains at least two components and includes an uppercase character. This bypasses public suffix protections and could allow a malicious website to set cookies for domains it does not own, potentially leading to integrity issues such as session fixation.

Affected products

• Red Hat Enterprise Linux 10: all versions — fixed in 0:3.6.5-3.el10_0.6
• Red Hat Enterprise Linux 6: all versions
• Red Hat Enterprise Linux 7: all versions
• Red Hat Enterprise Linux 8: all versions
• Red Hat Enterprise Linux 9: all versions

How to fix

Upgrade to a fixed version: Red Hat Enterprise Linux 10 0:3.6.5-3.el10_0.6. Check the vendor advisory for mitigations.

References

• https://access.redhat.com/errata/RHSA-2025:8128
• https://access.redhat.com/security/cve/CVE-2025-4035
• https://bugzilla.redhat.com/show_bug.cgi?id=2362651
• https://gitlab.gnome.org/GNOME/libsoup/-/issues/443
• https://gitlab.gnome.org/GNOME/libsoup/-/work_items/443

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