DoS in Libssh: Zero Max Packet Size Loop in SSH_MSG_CHANNEL_OPEN
CVE-2026-59843 Published on July 21, 2026
Libssh: libssh: denial of service via zero advertised channel packet size
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.
Vulnerability Analysis
CVE-2026-59843 can be exploited with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.
Timeline
Reported to Red Hat.
Made public. 83 days later.
Products Associated with CVE-2026-59843
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