Linux KernelOperating system · Linux

CVE-2025-38196

MEDIUM · 5.5 CVSS v3.1 Published 2025-07-04

Fix available

A fix is available. Upgrade to 6.15.4 or later.

See remediation →

57/100

Remediation priority · Elevated

Zero-click Patch available

Official description

NVD · unedited

In the Linux kernel, the following vulnerability has been resolved: io_uring/rsrc: validate buffer count with offset for cloning syzbot reports that it can trigger a WARN_ON() for kmalloc() attempt that's too big: WARNING: CPU: 0 PID: 6488 at mm/slub.c:5024 __kvmalloc_node_noprof+0x520/0x640 mm/slub.c:5024 Modules linked in: CPU: 0 UID: 0 PID: 6488 Comm: syz-executor312 Not tainted 6.15.0-rc7-syzkaller-gd7fa1af5b33e #0 PREEMPT Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 pstate: 20400005 (nzCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : __kvmalloc_node_noprof+0x520/0x640 mm/slub.c:5024 lr : __do_kmalloc_node mm/slub.c:-1 [inline] lr : __kvmalloc_node_noprof+0x3b4/0x640 mm/slub.c:5012 sp : ffff80009cfd7a90 x29: ffff80009cfd7ac0 x28: ffff0000dd52a120 x27: 0000000000412dc0 x26: 0000000000000178 x25: ffff7000139faf70 x24: 0000000000000000 x23: ffff800082f4cea8 x22: 00000000ffffffff x21: 000000010cd004a8 x20: ffff0000d75816c0 x19: ffff0000dd52a000 x18: 00000000ffffffff x17: ffff800092f39000 x16: ffff80008adbe9e4 x15: 0000000000000005 x14: 1ffff000139faf1c x13: 0000000000000000 x12: 0000000000000000 x11: ffff7000139faf21 x10: 0000000000000003 x9 : ffff80008f27b938 x8 : 0000000000000002 x7 : 0000000000000000 x6 : 0000000000000000 x5 : 00000000ffffffff x4 : 0000000000400dc0 x3 : 0000000200000000 x2 : 000000010cd004a8 x1 : ffff80008b3ebc40 x0 : 0000000000000001 Call trace: __kvmalloc_node_noprof+0x520/0x640 mm/slub.c:5024 (P) kvmalloc_array_node_noprof include/linux/slab.h:1065 [inline] io_rsrc_data_alloc io_uring/rsrc.c:206 [inline] io_clone_buffers io_uring/rsrc.c:1178 [inline] io_register_clone_buffers+0x484/0xa14 io_uring/rsrc.c:1287 __io_uring_register io_uring/register.c:815 [inline] __do_sys_io_uring_register io_uring/register.c:926 [inline] __se_sys_io_uring_register io_uring/register.c:903 [inline] __arm64_sys_io_uring_register+0x42c/0xea8 io_uring/register.c:903 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x58/0x17c arch/arm64/kernel/entry-common.c:767 el0t_64_sync_handler+0x78/0x108 arch/arm64/kernel/entry-common.c:786 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600 which is due to offset + buffer_count being too large. The registration code checks only the total count of buffers, but given that the indexing is an array, it should also check offset + count. That can't exceed IORING_MAX_REG_BUFFERS either, as there's no way to reach buffers beyond that limit. There's no issue with registrering a table this large, outside of the fact that it's pointless to register buffers that cannot be reached, and that it can trigger this kmalloc() warning for attempting an allocation that is too large.

Technical summary

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions

NVD · CPE data

Linux KernelOperating system

Affected:>= 6.13, < 6.15.4= 6.16

CVSS breakdown

From the vector

Attack vector: Local
Complexity: Low
Privileges: Low
User interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Remediation

dbcve · scoped

Upgrade available Upgrade to 6.15.4 or later

Fixed in 6.15.4

Vendor patch git.kernel.org →

Recommended fix High confidence

Linux Kernel 6.15.4 or later (or 6.16.1+ if available)

Upgrade the Linux kernel to version 6.15.4 or later, or to a version newer than 6.16 that includes the fix
After upgrading, verify the kernel version using 'uname -r'

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,600. Get the upgrade done

Scan for this in your stack

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References

Primary sources

git.kernel.orgPatch / commit
git.kernel.orgPatch
git.kernel.orgPatch
nvd.nist.govNVD record

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-38196 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2025-38196?

The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.

The version that genuinely resolved it — not the one the vendor claimed
A config change or rule that shut the vector down
A gotcha in the upgrade path that cost you an afternoon

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here

Verified mitigations, workarounds, and config changes
Version or environment caveats, and links to real fixes
No weaponised exploit code, or anything meant to cause harm
No spam, self-promotion, credentials, or personal data

At a glance

A fix existsUpgrade to 6.15.4 or later

Severity 5.5 Medium

Exploit likelihood EPSS, next 30 days 0.1%

Affects: Linux Kernel

Remediation

Need this fixed?

Get a fix

Estimated effortfrom ~9 hrs

ComplexityModerate

Typical engagementfrom $1,600

What a fix involves

We scope it with you and confirm a fixed quote
A specialist builds a reviewed fix
You deploy it to staging first
Optional re-test once it’s live

We specialise in CVE remediation. Send your environment and we’ll scope CVE-2025-38196 and return a fixed quote.

You’ll deal with our team directly and deploy the reviewed fix to staging first — never straight to production.

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

Scan for this in your stack

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Practitioner notes

No notes yet

Official description

Technical summary

Affected products & versions

CVSS breakdown

Remediation

References