Unauthorized Channel Creation Vulnerability in libssh
Summary
ALPINE-CVE-2018-10933: A vulnerability was found in libssh's server-side state machine before versions 0.7.6 and 0.8.4. Affects libssh versions < 0.7.6-r0. Fixed in 0.7.6-r0. How to fix ↓
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Background
libssh is a widely used library that implements the SSH protocol, allowing secure communication over unsecured networks. It provides functionalities for both client and server-side operations, enabling secure file transfers, remote command execution, and secure shell access. The library is crucial for applications requiring secure data transmission. However, prior to versions 0.7.6 and 0.8.4, libssh had a vulnerability in its server-side state machine that allowed malicious clients to create channels without authentication, posing a significant security risk.
Vulnerability Detail
A vulnerability was identified in libssh's server-side state machine before versions 0.7.6 and 0.8.4. This flaw allows a malicious client to create channels without prior authentication, leading to unauthorized access. The vulnerability stems from improper handling of client requests, which can result in a breach of security protocols. The potential ramifications include unauthorized data access and manipulation, making it critical for users to address this issue promptly. The CVSS score for this vulnerability is 9.1, indicating a high severity level.
How To Fix
Minimum fixed version
0.7.6-r0
This is the first release that contains the fix.
sudo apk add --upgrade libsshTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, it is recommended to restrict access to the libssh service until the package can be updated. This can be done by modifying firewall rules to limit connections to trusted IP addresses only.
Conclusion
The vulnerability in libssh's server-side state machine poses a significant risk by allowing unauthorized channel creation. It is crucial for users to update to the patched version to mitigate this risk. Additionally, utilizing tools like Vulert can help monitor and manage vulnerabilities effectively.
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FAQ
The vulnerability allows unauthorized clients to create channels, potentially leading to unauthorized access and data breaches.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without requiring any signup.
Versions of libssh prior to 0.7.6 and 0.8.4 are affected by this vulnerability.
Yes, you can restrict access to the libssh service by modifying firewall rules to limit connections to trusted IP addresses.
Vulert monitors and alerts in real-time for open-source vulnerabilities using just a manifest file like package-lock.json, helping developers maintain secure applications.
References
Related vulnerabilities
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