CVE-2026-59843
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.
Does this matter?
Lower severity and a low EPSS score (0.73%). Track it; it rarely justifies an emergency change on its own.
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.
- CVSS 3.1
- 6.5 MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 0.73% probability · 54th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-835, CWE-400
- Affected
- libssh/libssh · redhat/hardened images · redhat/enterprise linux
- Source
- secalert@redhat.com
EPSS 0.7% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://access.redhat.com/errata/RHSA-2026:42922Vendor Advisory
- https://access.redhat.com/errata/RHSA-2026:55855
- https://access.redhat.com/errata/RHSA-2026:62217
- https://access.redhat.com/errata/RHSA-2026:62218
- https://access.redhat.com/security/cve/CVE-2026-59843Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2498176Issue Tracking, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.