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

CVE-2026-27459

  • pyOpenSSL
High
7.2/10

Summary

If a user provided callback to `set_cookie_generate_callback` returned a cookie value greater than 256 bytes, pyOpenSSL would overflow an OpenSSL provided buffer. Cookie values that are too long are now rejected. This issue affects pyOpenSSL versions 22.0.0 prior to 26.0.0.

  • LOW
  • NETWORK
  • HIGH
  • UNCHANGED
  • NONE
  • NONE
  • HIGH
  • 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