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Time-of-check Time-of-use (TOCTOU) Race Condition

CVE-2021-4001

Medium
4.1/10

Summary

A race condition was found in the Linux kernel's ebpf verifier between bpf_map_update_elem and bpf_map_freeze due to a missing lock in kernel/bpf/syscall.c. In this flaw, a local user with a special privilege (cap_sys_admin or cap_bpf) can modify the frozen mapped address space. This flaw affects kernel versions prior to 5.16 rc2.

  • HIGH
  • LOCAL
  • HIGH
  • UNCHANGED
  • NONE
  • HIGH
  • NONE
  • NONE

CWE-367 - Time-of-check Time-of-use (TOCTOU) Race Condition

The software checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. This can cause the software to perform invalid actions when the resource is in an unexpected state.

References

Advisory Timeline

  • Published