CVE-2025-40052

UNRATEDCVSS · not yet scored
—
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • No CVSS published and no exploitation signals yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS v2: —Exploit: None knownExposed: 0

A fix is available — apply it.

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

smb: client: fix crypto buffers in non-linear memory

The crypto API, through the scatterlist API, expects input buffers to be in linear memory. We handle this with the cifs_sg_set_buf() helper that converts vmalloc'd memory to their corresponding pages.

However, when we allocate our aead_request buffer (@creq in smb2ops.c::crypt_message()), we do so with kvzalloc(), which possibly puts aead_request->__ctx in vmalloc area.

AEAD algorithm then uses ->__ctx for its private/internal data and operations, and uses sg_set_buf() for such data on a few places.

This works fine as long as @creq falls into kmalloc zone (small requests) or vmalloc'd memory is still within linear range.

Tasks' stacks are vmalloc'd by default (CONFIG_VMAP_STACK=y), so too many tasks will increment the base stacks' addresses to a point where virt_addr_valid(buf) will fail (BUG() in sg_set_buf()) when that happens.

In practice: too many parallel reads and writes on an encrypted mount will trigger this bug.

To fix this, always alloc @creq with kmalloc() instead. Also drop the @sensitive_size variable/arguments since kfree_sensitive() doesn't need it.

Backtrace:

[ 945.272081] ------------[ cut here ]------------ [ 945.272774] kernel BUG at include/linux/scatterlist.h:209! [ 945.273520] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC NOPTI [ 945.274412] CPU: 7 UID: 0 PID: 56 Comm: kworker/u33:0 Kdump: loaded Not tainted 6.15.0-lku-11779-g8e9d6efccdd7-dirty #1 PREEMPT(voluntary) [ 945.275736] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-2-gc13ff2cd-prebuilt.qemu.org 04/01/2014 [ 945.276877] Workqueue: writeback wb_workfn (flush-cifs-2) [ 945.277457] RIP: 0010:crypto_gcm_init_common+0x1f9/0x220 [ 945.278018] Code: b0 00 00 00 48 83 c4 08 5b 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc 48 c7 c0 00 00 00 80 48 2b 05 5c 58 e5 00 e9 58 ff ff ff <0f> 0b 0f 0b 0f 0b 0f 0b 0f 0b 0f 0b 48 c7 04 24 01 00 00 00 48 8b [ 945.279992] RSP: 0018:ffffc90000a27360 EFLAGS: 00010246 [ 945.280578] RAX: 0000000000000000 RBX: ffffc90001d85060 RCX: 0000000000000030 [ 945.281376] RDX: 0000000000080000 RSI: 0000000000000000 RDI: ffffc90081d85070 [ 945.282145] RBP: ffffc90001d85010 R08: ffffc90001d85000 R09: 0000000000000000 [ 945.282898] R10: ffffc90001d85090 R11: 0000000000001000 R12: ffffc90001d85070 [ 945.283656] R13: ffff888113522948 R14: ffffc90001d85060 R15: ffffc90001d85010 [ 945.284407] FS: 0000000000000000(0000) GS:ffff8882e66cf000(0000) knlGS:0000000000000000 [ 945.285262] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 945.285884] CR2: 00007fa7ffdd31f4 CR3: 000000010540d000 CR4: 0000000000350ef0 [ 945.286683] Call Trace: [ 945.286952] [ 945.287184] ? crypt_message+0x33f/0xad0 [cifs] [ 945.287719] crypto_gcm_encrypt+0x36/0xe0 [ 945.288152] crypt_message+0x54a/0xad0 [cifs] [ 945.288724] smb3_init_transform_rq+0x277/0x300 [cifs] [ 945.289300] smb_send_rqst+0xa3/0x160 [cifs] [ 945.289944] cifs_call_async+0x178/0x340 [cifs] [ 945.290514] ? __pfx_smb2_writev_callback+0x10/0x10 [cifs] [ 945.291177] smb2_async_writev+0x3e3/0x670 [cifs] [ 945.291759] ? find_held_lock+0x32/0x90 [ 945.292212] ? netfs_advance_write+0xf2/0x310 [ 945.292723] netfs_advance_write+0xf2/0x310 [ 945.293210] netfs_write_folio+0x346/0xcc0 [ 945.293689] ? __pfx__raw_spin_unlock_irq+0x10/0x10 [ 945.294250] netfs_writepages+0x117/0x460 [ 945.294724] do_writepages+0xbe/0x170 [ 945.295152] ? find_held_lock+0x32/0x90 [ 945.295600] ? kvm_sched_clock_read+0x11/0x20 [ 945.296103] __writeback_single_inode+0x56/0x4b0 [ 945.296643] writeback_sb_inodes+0x229/0x550 [ 945.297140] __writeback_inodes_wb+0x4c/0xe0 [ 945.297642] wb_writeback+0x2f1/0x3f0 [ 945.298069] wb_workfn+0x300/0x490 [ 945.298472] process_one_work+0x1fe/0x590 [ 945.298949] worker_thread+0x1ce/0x3c0 [ 945.299397] ? __pfx_worker_thread+0x10/0x10 [ 945.299900] kthr ---truncated---

CVSS v3
—
EchelonGraph score
Not yet assessedNo source has published severity data for this CVE yet — no CVSS score from NVD or a CNA, no GitHub advisory, and it is not in CISA KEV. This is not a rating of zero; we cannot assess it yet.
EG Score
—
EG Risk
—
EPSS PROB
0%
EPSS %ILE
10%
KEV
Not listed

Published

October 28, 2025

Last Modified

April 15, 2026

References (4)

Patch Availability(16)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-virtual-6.8 (6.8.0-106.106) @ noble2026-05-21ubuntu
ubuntulinux-tools-azure-6.17 (6.17.0-1008.8) @ questing2026-05-21ubuntu
ubuntulinux-tools-oem-6.17 (6.17.0-1011.11) @ noble2026-05-21ubuntu
ubuntulinux-tools-gcp-64k-6.17 (6.17.0-1007.7) @ questing2026-05-21ubuntu
ubuntulinux-virtual-hwe-24.04-edge (6.17.0-14.14) @ questing2026-05-21ubuntu
ubuntulinux-tools-oracle-64k-6.17 (6.17.0-1007.7) @ questing2026-05-21ubuntu
ubuntulinux-tools-nvidia-lowlatency-64k-6.8 (6.8.0-1049.52.1) @ noble2026-05-21ubuntu
ubuntulinux-tools-aws-edge (6.8.0-1050.53~22.04.1) @ jammy2026-05-21ubuntu
ubuntulinux-tools-realtime-6.8.1 (6.8.1-1045.46) @ noble2026-05-21ubuntu
ubuntulinux-tools-azure-lts-24.04 (6.8.0-1051.57) @ noble2026-05-21ubuntu
ubuntulinux-tools-gcp-fips-6.8 (6.8.0-1052.55+fips1) @ noble2026-05-21ubuntu
ubuntulinux-tools-azure-edge (6.8.0-1051.57~22.04.1) @ jammy2026-05-21ubuntu
ubuntulinux-tools-raspi-realtime-6.8 (6.8.0-2040.41) @ noble2026-05-21ubuntu
ubuntulinux-tools-azure-fips-6.8 (6.8.0-1052.58+fips1) @ noble2026-05-21ubuntu
ubuntulinux-xilinx-zynqmp (6.8.0.1029.30) @ noble2026-05-21ubuntu
linuxKernel @ 6.6.112—osv

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

All Vendor Advisories

(16)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 6× in last 7d / 36× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 129 total refreshes for this CVE.

  1. 2026-08-04 15:09 UTCEPSS rescore
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Related CVEs(same product + same vendor)

Frequently asked(4)

What is CVE-2025-40052?
CVE-2025-40052 is a publicly disclosed vulnerability published on October 28, 2025. In the Linux kernel, the following vulnerability has been resolved: smb: client: fix crypto buffers in non-linear memory The crypto API, through the scatterlist API, expects input buffers to be in linear memory. We handle this with the cifssgset_buf() helper that converts vmalloc'd memory to their…
When was CVE-2025-40052 disclosed?
CVE-2025-40052 was first published in the National Vulnerability Database on October 28, 2025, with the most recent update on April 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-40052 actively exploited?
CVE-2025-40052 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 89.8% of all scored CVEs.
How do I remediate CVE-2025-40052?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-40052, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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