CVE-2025-4035

Libsoup: cookie domain validation bypass via uppercase characters in libsoup

MEDIUM
4.3
CVSS Score
Published: April 29, 2025 at 12:56 PM UTC
Updated: July 1, 2026 at 11:21 PM UTC
1 product affected across 1 vendorEnterprise Linux

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Severity
MEDIUM4.3
Exploit prediction
EPSS 0.4%
SSVC
PoC

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Vendor states this is fixed in 0:3.6.5-3.el10_0.6 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

4.3MEDIUMredhat
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
NONE
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-178

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