UltraVNC Viewer VNC client Remote Memory Leak Vulnerability


A vulnerability exists within UltraVNC view due to a lack of proper stack memory buffer cleanup before constructing the ‘rfbTextChat’ message, which results in a leak of 3-bytes of stack memory. An attacker can leverage this in conjunction with other vulnerabilities to execute code in the context of the UltraVNC Viewer process.

Vulnerability Identifiers

  • Exodus Intelligence: EIP-5182fb5b

Vulnerability Metrics

  • CVSSv2 Score: 4.3

Vendor References

Discovery Credit

  • Exodus Intelligence

Disclosure Timeline

  • Disclosed to affected vendor: June 21th, 2021
  • Disclosed to public: September 25th, 2021

Further Information

Readers of this advisory who are interested in receiving further details around the vulnerability, mitigations, detection guidance, and more can contact us at sales@exodusintel.com.

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