LiveActive security incident?Get immediate response
CVE Record

CVE-2025-38139: netfs: Fix oops in write-retry from mis-resetting the subreq iterator

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>

CriticalCVSS 9.8Not KEV-listedUpdated
Discuss exposureBack to CVEs
Glexia's TakeAutomated analysiscritical

Security readout for executives and security teams

Plain-English summary

A Linux netfs write-retry bookkeeping error can make the kernel read beyond an allocated buffer and crash. The supplied record rates it critical, but it does not establish that ordinary network access alone can trigger the flaw. Systems using affected kernels and netfs-backed filesystem writes deserve prompt review.

Executive priority

Treat this as an urgent kernel-maintenance issue where affected netfs functionality is used, while avoiding assumptions of widespread remote compromise. Establish exact vendor exposure first, then patch critical systems promptly. Other systems can follow risk-based maintenance once their kernel fix status and workload relevance are confirmed.

Technical view

netfs_retry_write_stream() incorrectly reset a shortened subrequest iterator using the original subrequest length instead of accounting for bytes already transferred. During a later write retry, iov_iter_revert() could access beyond the slab allocation. KASAN reproduced the defect in a syzkaller kernel worker. The referenced Linux stable commits correct the iterator reset.

Likely exposure

The bundle identifies Linux kernel versions around 6.12 through 6.16 as affected, but its flattened version list does not clearly preserve exact fixed-version boundaries. Exposure depends on whether a deployed kernel contains the vulnerable netfs code and lacks the referenced fix or a distribution backport. Prioritize systems performing netfs-backed writes.

Exploitation context

The supplied evidence shows a syzkaller/KASAN-triggered slab-out-of-bounds read and possible kernel oops. KEV is false, and no cited source establishes active exploitation, a public exploit, reliable remote reachability, privilege escalation, or data compromise. The CVSS network vector should not be treated alone as proof of practical remote exploitation.

Researcher notes

The demonstrated failure occurs in asynchronous netfs write collection after an iterator was shortened by a prior retry. The record supports an out-of-bounds read and oops, but not the supplied CVSS confidentiality, integrity, and availability impacts individually. Exact vulnerable ranges, trigger prerequisites, and security consequences remain insufficiently documented in the bundle.

Mitigation direction

  • Apply a vendor kernel update containing the referenced fix or an equivalent backport.
  • Check distribution advisories for exact affected and corrected package versions.
  • Prioritize internet-facing and business-critical systems using netfs-backed filesystem writes.
  • If updates are unavailable, obtain vendor guidance before adopting temporary operational workarounds.

Validation and detection

  • Inventory kernel versions and distribution package revisions across potentially exposed systems.
  • Verify whether kernel sources or vendor packages include one of the referenced stable fixes.
  • Review kernel logs for iov_iter_revert, netfs write-retry, KASAN, or unexplained oops messages.
  • Run approved filesystem write-retry regression tests in an isolated non-production environment after updating.
Prepared
Confidence
medium
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cve · low confidence lookup

CVE-2025-38139 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
Critical
CVSS
9.8 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
3Timeline events
0ADP providers
4Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
9.8CVSS 3.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

9.8Critical
CVSS 3.1 vector shape for CVE-2025-38139Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxcd0277ed0c188dd40e7744e89299af7b78831ca4, cd0277ed0c188dd40e7744e89299af7b78831ca4, cd0277ed0c188dd40e7744e89299af7b78831ca4unaffected
LinuxLinux6.12, 0, 6.12.37, 6.15.3, 6.16affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.