Missing Release of Resource after Effective Lifetime Affecting kernel6.18-tools-devel package, versions <1:6.18.39-79.141.amzn2023


Severity

Recommended
high

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.17% (7th percentile)

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  • Snyk IDSNYK-AMZN2023-KERNEL618TOOLSDEVEL-18908802
  • published18 Aug 2026
  • disclosed25 Jul 2026

Introduced: 25 Jul 2026

NewCVE-2026-64426  (opens in a new tab)
CWE-772  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 kernel6.18-tools-devel to version 1:6.18.39-79.141.amzn2023 or higher.
This issue was patched in ALAS2023-2026-2045.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel6.18-tools-devel package and not the kernel6.18-tools-devel package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

io_uring/nop: fix file reference leak with IOSQE_FIXED_FILE

NOP file-acquisition support choses between a fixed (registered) file and a normal fget()'d file based on its own IORING_NOP_FIXED_FILE flag in sqe->nop_flags. However, a request's REQ_F_FIXED_FILE is set independently from the generic IOSQE_FIXED_FILE sqe flag during request init, before the issue handler runs.

If a NOP is submitted with IOSQE_FIXED_FILE set (so REQ_F_FIXED_FILE is set) but without IORING_NOP_FIXED_FILE, io_nop() takes the normal path and grabs a real reference via io_file_get_normal(). On completion, io_put_file() only drops the reference when REQ_F_FIXED_FILE is clear, so the fget()'d file is never released and leaks:

BUG: memory leak unreferenced object 0xffff88800f42c240 (size 176): kmem_cache_alloc_noprof+0x358/0x440 alloc_empty_file+0x57/0x180 path_openat+0x44/0x1e50 do_file_open+0x121/0x200 do_sys_openat2+0xa7/0x150 __x64_sys_openat+0x82/0xf0

Decide between fixed and normal file acquisition from REQ_F_FIXED_FILE, the same way io_assign_file() does for every other opcode, and fold IORING_NOP_FIXED_FILE into REQ_F_FIXED_FILE at prep time.

CVSS Base Scores

version 3.1