Linux Kernel up to 6.18.38/7.1.3 io_uring io_nop nop_flags memory leak

CVSS Meta Temp Score
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CTI Interest Score
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5.3$0-$5k1.60

Summaryinfo

A vulnerability has been found in Linux Kernel up to 6.18.38/7.1.3 and classified as critical. Affected by this issue is the function io_nop of the file io_uring of the component io_uring. This manipulation of the argument nop_flags causes memory leak. This vulnerability is tracked as CVE-2026-64426. The attack is restricted to local execution. No exploit exists.

Detailsinfo

A vulnerability has been found in Linux Kernel up to 6.18.38/7.1.3 and classified as critical. Affected by this vulnerability is the function io_nop of the file io_uring of the component io_uring. The manipulation of the argument nop_flags with an unknown input leads to a memory leak vulnerability. The CWE definition for the vulnerability is CWE-401. The product does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory. As an impact it is known to affect availability. The summary by CVE is:

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.

The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2026-64426 since 07/19/2026. The exploitation appears to be easy. An attack has to be approached locally. Technical details are known, but no exploit is available.

Upgrading to version 6.18.39, 7.1.4 or 7.2-rc1 eliminates this vulnerability. Applying the patch 722869fcff598fad20d5ab79c305897a7534708b/7267717f35787167fcce4bc14f6ef3fa06682dcf/2564ca2e31bd8ee8348362941af2ee4671e487ca is able to eliminate this problem.

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Productinfo

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Version

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.5
VulDB Meta Temp Score: 5.3

VulDB Base Score: 5.5
VulDB Temp Score: 5.3
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Memory leak
CWE: CWE-401 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.18.39/7.1.4/7.2-rc1
Patch: 722869fcff598fad20d5ab79c305897a7534708b/7267717f35787167fcce4bc14f6ef3fa06682dcf/2564ca2e31bd8ee8348362941af2ee4671e487ca

Timelineinfo

07/19/2026 CVE reserved
07/25/2026 +6 days Advisory disclosed
07/25/2026 +0 days VulDB entry created
07/25/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-64426 (🔒)
GCVE (CVE): GCVE-0-2026-64426
GCVE (VulDB): GCVE-100-383197

Entryinfo

Created: 07/25/2026 18:24
Changes: 07/25/2026 18:24 (61)
Complete: 🔍
Cache ID: 216::103

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