Medium [CVE-2026-59845] denial of service via unchecked ProxyCommand fork failure
This medium-severity Red Hat Linux advisory covers CVE-2026-59845 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9.
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Summary
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.
This Moderate flaw in libssh client-side ProxyCommand handling can lead to a local denial of service. This issue specifically impacts environments utilizing ProxyCommand functionality.
Red Hat severity: Moderate — CVSS 5.3 (CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:C/C:N/I:N/A:H). Weakness: CWE-390.
Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9; Red Hat Hardened Images. Red Hat fixing advisory: RHSA-2026:55855, RHSA-2026:62218, RHSA-2026:62217, RHSA-2026:42922.
Affected products named by the advisory: Red Hat package: libssh.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative. Check it before change work.
Official advisory · high-confidence parse· fetched 8 days ago·verify at source
- libssh-0:0.12.0-3.el10_2
- libssh-0:0.9.6-17.el8_10
- libssh-0:0.10.4-19.el9_8
- libssh-main-0.12.1-4.hum1
- RHSA-2026:55855
- RHSA-2026:62218
- RHSA-2026:62217
- RHSA-2026:42922
Official advisory · high-confidence parse· fetched 8 days ago·verify at source
Mitigation checklist
- 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.
Official advisory · high-confidence parse· fetched 8 days ago·verify at source
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