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.
Affected products
libssh: libssh; redhat: hardened images; redhat: enterprise linux
References6
- access.redhat.com/errata/RHSA-2026:42922 Vendor Advisory
- access.redhat.com/security/cve/CVE-2026-59843 Vendor Advisory
- bugzilla.redhat.com/show_bug.cgi?id=2498176 Issue TrackingVendor Advisory
- access.redhat.com/errata/RHSA-2026:55855
- access.redhat.com/errata/RHSA-2026:62217
- access.redhat.com/errata/RHSA-2026:62218
Metrics
- CVSS 3.1
-
6.5
MEDIUM
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - EPSS — exploit probability
- 1% percentile: 48 · as of 14 November 2026
- CWE
- CWE-835CWE-400
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.