CVE-2025-9901
Publication date 3 September 2025
Last updated 11 December 2025
Ubuntu priority
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.
Read the notes from the security team
Why is this CVE low priority?
Upstream has deemed this to be a low priority issue
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| libsoup3 | 25.10 questing |
Vulnerable, fix deferred
|
| 25.04 plucky |
Vulnerable, fix deferred
|
|
| 24.04 LTS noble |
Vulnerable, fix deferred
|
|
| 22.04 LTS jammy |
Vulnerable, fix deferred
|
|
| libsoup2.4 | 25.10 questing |
Vulnerable, fix deferred
|
| 25.04 plucky |
Vulnerable, fix deferred
|
|
| 24.04 LTS noble |
Vulnerable, fix deferred
|
|
| 22.04 LTS jammy |
Vulnerable, fix deferred
|
|
| 20.04 LTS focal |
Vulnerable, fix deferred
|
|
| 18.04 LTS bionic |
Vulnerable, fix deferred
|
|
| 16.04 LTS xenial |
Vulnerable, fix deferred
|
Notes
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score |
5.9 · Medium
|
| Attack vector | Network |
| Attack complexity | High |
| Privileges required | None |
| User interaction | None |
| Scope | Unchanged |
| Confidentiality | High |
| Integrity impact | None |
| Availability impact | None |
| Vector | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N |