CVE-2026-59845

Libssh: libssh: denial of service via unchecked proxycommand fork() failure

Published Jul 21, 2026 CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed
Description
A flaw was found in libssh. When ProxyCommand is used, an unchecked fork() failure can be stored as process ID -1; during cleanup, signals may then be sent across the caller's accessible process tree, leading to local denial of service.

Remediation

Vendor Workaround

To mitigate this issue, avoid using the ProxyCommand feature in libssh client configurations. This prevents the vulnerable code path from being exercised, thereby eliminating the risk of local denial of service due to unchecked fork() failures.

Tracking

Sign in to view the affected projects.

Advisories

Source ID Title
Debian DLA Debian DLA DLA-4844-1 libssh security update
Debian DSA Debian DSA DSA-6410-1 libssh security update
Ubuntu USN Ubuntu USN USN-8699-1 libssh vulnerabilities
History
Type Values Removed Values Added
CPEs cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:enterprise_linux:9
cpe:/a:redhat:enterprise_linux:8::appstream
cpe:/a:redhat:enterprise_linux:9::appstream
cpe:/o:redhat:enterprise_linux:8::baseos
cpe:/o:redhat:enterprise_linux:9::baseos
References
Type Values Removed Values Added
CPEs cpe:/o:redhat:enterprise_linux:10 cpe:/o:redhat:enterprise_linux:10.2
References
Type Values Removed Values Added
First Time appeared Libssh
Libssh libssh
Redhat hardened Images
Vendors & Products Libssh
Libssh libssh
Redhat hardened Images
Type Values Removed Values Added
Weaknesses CWE-390
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description A flaw was found in libssh. When ProxyCommand is used, an unchecked fork() failure can be stored as process ID -1; during cleanup, signals may then be sent across the caller's accessible process tree, leading to local denial of service.
Title Libssh: libssh: denial of service via unchecked proxycommand fork() failure
First Time appeared Redhat
Redhat enterprise Linux
Redhat hummingbird
CPEs cpe:/a:redhat:hummingbird:1
cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat
Redhat enterprise Linux
Redhat hummingbird
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:C/C:N/I:N/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
redhat
Published
Updated
Sep 1, 2026, 8:01 PM
Reserved
Jul 7, 2026, 3:40 PM
Status
Modified
Published
Jul 21, 2026, 12:18 PM
Modified
Sep 1, 2026, 9:18 PM
Severity
Moderate
Public date
Jul 21, 2026, 11:23 AM