---
id: CVE-2025-9901
title: >-
  A flaw was found in libsoup’s caching mechanism, SoupCache, where the HTTP
  Vary header is ignored when evaluating cached responses
summary: >-
  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
  authen…
severity: medium
cvss: 5.9
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N'
cwe:
  - CWE-524
published: '2025-09-03'
updated: '2026-06-25'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-9901'
references:
  - url: 'https://access.redhat.com/security/cve/CVE-2025-9901'
    label: secalert@redhat.com
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2392790'
    label: secalert@redhat.com
  - url: 'https://gitlab.gnome.org/GNOME/libsoup/-/issues/453'
    label: secalert@redhat.com
tags:
  - nvd
epss: 0.00457
epssPercentile: 0.38966
ingestedAt: '2026-06-29T13:24:34.408Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.