CESNET libyang Multiple Stack Based Buffer Overflow Vulnerabilities



Date Discovered

December 4, 2019


CESNET libyang is prone to multiple stack-based buffer-overflow vulnerabilities because it fails to adequately bounds-check user-supplied data before copying it to an insufficiently sized memory buffer. An attacker can exploit these issues to execute arbitrary code in the context of an affected system. Failed exploit attempts may result in a denial-of-service condition. Versions prior to CESNET libyang 1.0-r5 are vulnerable.

Technologies Affected

  • CESNET libyang 0.11-r1
  • CESNET libyang 0.12-r1
  • CESNET libyang 0.13-r1
  • CESNET libyang 0.14-r1
  • CESNET libyang 0.15-r1
  • CESNET libyang 0.16-r1
  • CESNET libyang 1.0-r1
  • CESNET libyang 1.0-r2
  • CESNET libyang 1.0-r4
  • Redhat Enterprise Linux 8


Block external access at the network boundary, unless external parties require service.
If global access isn't needed, filter access to the affected computer at the network boundary. Restricting access to only trusted computers and networks might greatly reduce the likelihood of successful exploits.

Run all software as a nonprivileged user with minimal access rights.
Run all non-administrative software as a non-administrative user with the least amount of privileges required to successfully operate. This will greatly reduce the potential damage that successful exploitation may achieve.

Deploy network intrusion detection systems to monitor network traffic for malicious activity.
Deploy NIDS to monitor network traffic for signs of anomalous or suspicious activity. This includes but is not limited to requests that include NOP sleds and unexplained incoming and outgoing traffic. This may indicate exploit attempts or activity that results from successful exploits.

Implement multiple redundant layers of security.
Various memory-protection schemes (such as nonexecutable and randomly mapped memory segments) may hinder an attacker's ability to exploit this vulnerability to execute arbitrary code.

Updates are available. Please see the references or vendor advisory for more information.



Riccardo Schirone (Red Hat Product Security).

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