Critical Buffer Overflow Vulnerability in PuTTY Package
Summary
ALPINE-CVE-2019-9895: In PuTTY versions before 0.71 on Unix, a remotely triggerable buffer overflow exists in any kind of server-to-client forwarding. Affects putty versions < 0.71-r0. Fixed in 0.71-r0. How to fix ↓
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Background
PuTTY is a widely used open-source terminal emulator, serial console, and network file transfer application. It supports various network protocols, including SSH, Telnet, and SCP, making it a vital tool for secure remote access and file transfers. However, versions prior to 0.71 are susceptible to a critical buffer overflow vulnerability that can be exploited remotely, posing significant security risks to users.
Vulnerability Detail
In PuTTY versions before 0.71 on Unix, a remotely triggerable buffer overflow exists in any kind of server-to-client forwarding. This vulnerability can allow an attacker to execute arbitrary code on the victim's machine, leading to unauthorized access, data breaches, or complete system compromise. The vulnerability arises from improper handling of data during server-to-client communication, which can overflow the buffer and overwrite adjacent memory.
How To Fix
Minimum fixed version
0.71-r0
This is the first release that contains the fix.
sudo apk add --upgrade puttyTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, users can disable server-to-client forwarding in PuTTY settings to prevent exploitation of this vulnerability until the package is updated. This can be done by navigating to the SSH settings and unchecking the 'Enable X11 forwarding' option.
Conclusion
The buffer overflow vulnerability in PuTTY versions prior to 0.71 poses a significant risk to users, allowing for potential remote code execution. It is crucial for users to update to the latest version to protect against this vulnerability. Additionally, utilizing tools like Vulert can help monitor and alert for open-source vulnerabilities in software applications.
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FAQ
The CVSS score of this vulnerability is 9.8, indicating a critical level of severity.
You can use Vulert's playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
Exploitation of this vulnerability can lead to unauthorized access, data breaches, and complete system compromise.
Yes, a patch is available in version 0.71 of PuTTY. Users should update to this version to mitigate the risk.
If immediate updating is not possible, consider disabling server-to-client forwarding as a temporary workaround.
References
Related vulnerabilities
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