Resource exhaustion in Libssh
CVE-2026-59843
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.
Published · last modified .
CVSS v3 metric
CVSS v3 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.
EPSS exploit prediction
EPSS: 0.007 (53.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 53rd percentile — 53.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.007 · change: +0.002
Affected products
- Libssh
- Red Hat Enterprise Linux 10 — versions 0:0.12.0-3.el10_2
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat Hardened Images — versions 0.12.1-4.hum1
- Red Hat Enterprise Linux — versions 8.0, 9.0, 10.0
- Red Hat Hardened Images
Weakness classification (CWE)
References
- access.redhat.com/security/cve/CVE-2026-59843 (vdb-entry, Vendor Advisory)
- bugzilla.redhat.com/show_bug.cgi (issue-tracking, Issue Tracking, Vendor Advisory)
- access.redhat.com/errata/RHSA-2026:42922 (vendor-advisory, Vendor Advisory)
- access.redhat.com/errata/RHSA-2026:55855 (vendor-advisory)
- access.redhat.com/errata/RHSA-2026:62218 (vendor-advisory)
- access.redhat.com/errata/RHSA-2026:62217 (vendor-advisory)
Frequently asked questions
- What is CVE-2026-59843?
- CVE-2026-59843 is a medium-severity vulnerability in Libssh, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 6.5/10. Published 2026-07-21.
- How severe is CVE-2026-59843?
- Medium severity. CVSS v3 base score is 6.5 out of 10.