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… (CVE-2026-59843)
A vulnerability in libssh allows a remote authenticated peer to advertise a zero maximum packet size in SSH_MSG_CHANNEL_OPEN, causing subsequent channel writes to enter an infinite loop that consumes CPU resources and leads to denial of service.
AI Analysis
Technical Summary
CVE-2026-59843 is a denial of service vulnerability in libssh where a remote authenticated peer can specify a zero maximum packet size in the SSH_MSG_CHANNEL_OPEN message. This causes later channel write operations to loop indefinitely, consuming CPU and potentially degrading service availability. The vulnerability is identified as CWE-835 (Loop with Unreachable Exit Condition) and CWE-400 (Uncontrolled Resource Consumption). The CVSS v3.1 base score is 6.5 (medium severity) with network attack vector, low complexity, low privileges required, no user interaction, unchanged scope, no confidentiality or integrity impact, and high availability impact. The affected version explicitly stated is libssh version 0.12.1-4.hum1. Red Hat has published advisories acknowledging the issue but no fix is currently available, and no workaround or mitigation exists.
Potential Impact
The vulnerability causes an infinite loop in libssh when processing a zero maximum packet size, leading to excessive CPU consumption and denial of service. There is no impact on confidentiality or integrity. The denial of service can degrade or disrupt services relying on libssh.
Mitigation Recommendations
No workaround or mitigation is currently available. Users should monitor Red Hat advisories for updates and apply any future patches once released.
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… (CVE-2026-59843)
Description
A vulnerability in libssh allows a remote authenticated peer to advertise a zero maximum packet size in SSH_MSG_CHANNEL_OPEN, causing subsequent channel writes to enter an infinite loop that consumes CPU resources and leads to denial of service.
CVSS v3.1
Score 6.5medium
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-59843 is a denial of service vulnerability in libssh where a remote authenticated peer can specify a zero maximum packet size in the SSH_MSG_CHANNEL_OPEN message. This causes later channel write operations to loop indefinitely, consuming CPU and potentially degrading service availability. The vulnerability is identified as CWE-835 (Loop with Unreachable Exit Condition) and CWE-400 (Uncontrolled Resource Consumption). The CVSS v3.1 base score is 6.5 (medium severity) with network attack vector, low complexity, low privileges required, no user interaction, unchanged scope, no confidentiality or integrity impact, and high availability impact. The affected version explicitly stated is libssh version 0.12.1-4.hum1. Red Hat has published advisories acknowledging the issue but no fix is currently available, and no workaround or mitigation exists.
Potential Impact
The vulnerability causes an infinite loop in libssh when processing a zero maximum packet size, leading to excessive CPU consumption and denial of service. There is no impact on confidentiality or integrity. The denial of service can degrade or disrupt services relying on libssh.
Mitigation Recommendations
No workaround or mitigation is currently available. Users should monitor Red Hat advisories for updates and apply any future patches once released.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-4846-7xwg-pw5m
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-59843"]
- Database Specific Severity
- MODERATE
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6a6150e69c2644c7f8da1e83
Added to database: 07/22/2026, 23:23:18 UTC
Last enriched: 09/13/2026, 20:04:41 UTC
Last updated: 09/14/2026, 10:01:32 UTC
Views: 107
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