CVE-2023-0240: Use after free in io_uring in the Linux Kernel

Vulnerability summary

CVE-2023-0240 is a high (CVSS 7.8) Use After Free vulnerability in linux linux_kernel. EPSS estimates a 0.27% chance of exploitation in the next 30 days, higher than 19.4% of scored vulnerabilities.

Timeline

1. 30-01-2023
   PublishedVulnerability first disclosed.
2. 02-08-2024
   Last modifiedVulnerability information updated.

Description

There is a logic error in io_uring's implementation which can be used to trigger a use-after-free vulnerability leading to privilege escalation. In the io_prep_async_work function the assumption that the last io_grab_identity call cannot return false is not true, and in this case the function will use the init_cred or the previous linked requests identity to do operations instead of using the current identity. This can lead to reference counting issues causing use-after-free. We recommend upgrading past version 5.10.161.

• CWE-416Use After FreeThe product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.