CVE-2026-33555
Publication date 13 April 2026
Last updated 27 April 2026
Ubuntu priority
Description
An issue was discovered in HAProxy before 3.3.6. The HTTP/3 parser does not check that the received body length matches a previously announced content-length when the stream is closed via a frame with an empty payload. This can cause desynchronization issues with the backend server and could be used for request smuggling. The earliest affected version is 2.6.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| haproxy | 26.04 LTS resolute |
Fixed 3.2.9-1ubuntu2.1
|
| 25.10 questing |
Fixed 3.0.12-0ubuntu0.25.10.4
|
|
| 24.04 LTS noble |
Fixed 2.8.16-0ubuntu0.24.04.2
|
|
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal |
Not affected
|
|
| 18.04 LTS bionic |
Not affected
|
|
| 16.04 LTS xenial |
Not affected
|
Patch details
| Package | Patch details |
|---|---|
| haproxy |
|
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score |
4.0 · Medium
|
| Attack vector | Network |
| Attack complexity | High |
| Privileges required | None |
| User interaction | None |
| Scope | Changed |
| Confidentiality | None |
| Integrity impact | Low |
| Availability impact | None |
| Vector | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N |