CVE-2026-59843
Publication date 21 July 2026
Last updated 31 August 2026
Ubuntu priority
Description
A flaw was found in libssh. A remote authenticated peer can advertise a zero maximum packet size in SSH_MSG_CHANNEL_OPEN, causing later channel writes to loop indefinitely and consume CPU, leading to denial of service.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| libssh | 26.04 LTS resolute |
Fixed 0.11.3-1ubuntu2.1
|
| 24.04 LTS noble |
Fixed 0.10.6-2ubuntu0.5
|
|
| 22.04 LTS jammy |
Fixed 0.9.6-2ubuntu0.22.04.8
|
|
| 20.04 LTS focal |
Needs evaluation
|
|
| 18.04 LTS bionic |
Needs evaluation
|
|
| 16.04 LTS xenial |
Needs evaluation
|
Notes
mdeslaur
While this was mentioned in the 0.12.1 release notes, it was accidentally omitted and was included in 0.12.2 instead.
Severity score breakdown
CVSS version: CVSS v3.0
Base score
6.5 · Medium
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
References
Related Ubuntu Security Notices (USN)
- USN-8699-1
- libssh vulnerabilities
- 31 August 2026