CVE-2025-38139: Linux Kernel out-of-bounds read (CVSS 9.8)

Description

In the Linux kernel, the following vulnerability has been resolved: netfs: Fix oops in write-retry from mis-resetting the subreq iterator Fix the resetting of the subrequest iterator in netfs_retry_write_stream() to use the iterator-reset function as the iterator may have been shortened by a previous retry. In such a case, the amount of data to be written by the subrequest is not "subreq->len" but "subreq->len - subreq->transferred". Without this, KASAN may see an error in iov_iter_revert(): BUG: KASAN: slab-out-of-bounds in iov_iter_revert lib/iov_iter.c:633 [inline] BUG: KASAN: slab-out-of-bounds in iov_iter_revert+0x443/0x5a0 lib/iov_iter.c:611 Read of size 4 at addr ffff88802912a0b8 by task kworker/u32:7/1147 CPU: 1 UID: 0 PID: 1147 Comm: kworker/u32:7 Not tainted 6.15.0-rc6-syzkaller-00052-g9f35e33144ae #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Workqueue: events_unbound netfs_write_collection_worker Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:408 [inline] print_report+0xc3/0x670 mm/kasan/report.c:521 kasan_report+0xe0/0x110 mm/kasan/report.c:634 iov_iter_revert lib/iov_iter.c:633 [inline] iov_iter_revert+0x443/0x5a0 lib/iov_iter.c:611 netfs_retry_write_stream fs/netfs/write_retry.c:44 [inline] netfs_retry_writes+0x166d/0x1a50 fs/netfs/write_retry.c:231 netfs_collect_write_results fs/netfs/write_collect.c:352 [inline] netfs_write_collection_worker+0x23fd/0x3830 fs/netfs/write_collect.c:374 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c2/0x780 kernel/kthread.c:464 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 </TASK>

CVSS 3.1 breakdown

Attack vectorNetwork

Attack complexityLow

Privileges requiredNone

User interactionNone

ScopeUnchanged

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Affected products

Linux Kernel≥ 6.12 < 6.12.37 · ≥ 6.13 < 6.15.3

Remediation

Fixed in

Linux Kernel≥ 6.12.37

Patch & vendor advisories

References

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

Frequently asked

Is CVE-2025-38139 being actively exploited?

CVE-2025-38139 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.45%.

How severe is CVE-2025-38139?

CVE-2025-38139 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 0.45% probability of exploitation.

Which products are affected by CVE-2025-38139?

Affected products include Linux Kernel.

How do I fix CVE-2025-38139?

Upgrade affected software to a fixed version, for example Linux Kernel 6.12.37 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2025-38139 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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