CVE-2026-85534
Publication date 4 September 2026
Last updated 21 October 2026
Ubuntu priority
Description
A flaw was found in libsoup. When a client sends an HTTP/2 request body from a non-pollable input stream, the library can buffer more data than the current flow-control window later allows. A malicious HTTP/2 server can shrink SETTINGS_INITIAL_WINDOW_SIZE while that buffered read is still in progress. The client then copies the full buffer into a smaller DATA callback without a runtime bounds check, which can abort the process or fail the HTTP/2 session.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| libsoup2.4 | 26.10 stonking |
Not affected
|
| 26.04 LTS resolute |
Not affected
|
|
| 24.04 LTS noble |
Not affected
|
|
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal |
Not affected
|
|
| 18.04 LTS bionic |
Not affected
|
|
| 16.04 LTS xenial |
Not affected
|
|
| libsoup3 | 26.10 stonking |
Fixed in 3.6.6-1ubuntu3
|
| 26.04 LTS resolute |
Fixed in 3.6.6-1ubuntu0.1
|
|
| 24.04 LTS noble |
Fixed in 3.4.4-5ubuntu0.9
|
|
| 22.04 LTS jammy |
Fixed in 3.0.7-0ubuntu1+esm9
|
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CVSS version: CVSS v3.0
Base score
5.9 · Medium
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
References
Related Ubuntu Security Notices (USN)
- USN-8890-1
- libsoup vulnerabilities
- 6 October 2026
- USN-8890-2
- libsoup vulnerabilities
- 21 October 2026