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Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

CVE-2021-34557

Medium
4.6/10

Summary

XScreenSaver 5.45 can be bypassed if the machine has more than ten disconnectable video outputs. A buffer overflow in update_screen_layout() allows an attacker to bypass the standard screen lock authentication mechanism by crashing XScreenSaver. The attacker must physically disconnect many video outputs.

  • LOW
  • PHYSICAL
  • NONE
  • UNCHANGED
  • NONE
  • NONE
  • NONE
  • HIGH

CWE-120 - Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

The program copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow.

References

Advisory Timeline

  • Published