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Linux Kernel CVE-2025-40000

HIGH
2025-10-15 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Information Disclosure Linux Red Hat Suse
8.8
CVSS 3.1 · Vendor: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
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Severity by source

Vendor (416baaa9-dc9f-4396-8d5f-8c081fb06d67) PRIMARY
8.8 HIGH
AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
vuln.today AI
6.8 MEDIUM

Adjacent Wi-Fi driver path (AV:A); a hard-to-win completion race gives AC:H; no auth needed (PR:N); UAF write yields integrity/availability impact but no clear disclosure (C:N).

3.1 AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H
4.0 AV:A/AC:H/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N
SUSE
5.5 MEDIUM
AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Red Hat
6.3 MEDIUM
qualitative

Primary rating from Vendor (416baaa9-dc9f-4396-8d5f-8c081fb06d67).

CVSS VectorVendor: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Attack Vector
Adjacent
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

2
Analysis Generated
Jul 30, 2026 - 08:01 vuln.today
CVE Published
Oct 15, 2025 - 08:15 cve.org
HIGH 8.8

DescriptionCVE.org

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

wifi: rtw89: fix use-after-free in rtw89_core_tx_kick_off_and_wait()

There is a bug observed when rtw89_core_tx_kick_off_and_wait() tries to access already freed skb_data:

BUG: KFENCE: use-after-free write in rtw89_core_tx_kick_off_and_wait drivers/net/wireless/realtek/rtw89/core.c:1110

CPU: 6 UID: 0 PID: 41377 Comm: kworker/u64:24 Not tainted 6.17.0-rc1+ #1 PREEMPT(lazy) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS edk2-20250523-14.fc42 05/23/2025 Workqueue: events_unbound cfg80211_wiphy_work [cfg80211]

Use-after-free write at 0x0000000020309d9d (in kfence-#251): rtw89_core_tx_kick_off_and_wait drivers/net/wireless/realtek/rtw89/core.c:1110 rtw89_core_scan_complete drivers/net/wireless/realtek/rtw89/core.c:5338 rtw89_hw_scan_complete_cb drivers/net/wireless/realtek/rtw89/fw.c:7979 rtw89_chanctx_proceed_cb drivers/net/wireless/realtek/rtw89/chan.c:3165 rtw89_chanctx_proceed drivers/net/wireless/realtek/rtw89/chan.h:141 rtw89_hw_scan_complete drivers/net/wireless/realtek/rtw89/fw.c:8012 rtw89_mac_c2h_scanofld_rsp drivers/net/wireless/realtek/rtw89/mac.c:5059 rtw89_fw_c2h_work drivers/net/wireless/realtek/rtw89/fw.c:6758 process_one_work kernel/workqueue.c:3241 worker_thread kernel/workqueue.c:3400 kthread kernel/kthread.c:463 ret_from_fork arch/x86/kernel/process.c:154 ret_from_fork_asm arch/x86/entry/entry_64.S:258

kfence-#251: 0x0000000056e2393d-0x000000009943cb62, size=232, cache=skbuff_head_cache

allocated by task 41377 on cpu 6 at 77869.159548s (0.009551s ago): __alloc_skb net/core/skbuff.c:659 __netdev_alloc_skb net/core/skbuff.c:734 ieee80211_nullfunc_get net/mac80211/tx.c:5844 rtw89_core_send_nullfunc drivers/net/wireless/realtek/rtw89/core.c:3431 rtw89_core_scan_complete drivers/net/wireless/realtek/rtw89/core.c:5338 rtw89_hw_scan_complete_cb drivers/net/wireless/realtek/rtw89/fw.c:7979 rtw89_chanctx_proceed_cb drivers/net/wireless/realtek/rtw89/chan.c:3165 rtw89_chanctx_proceed drivers/net/wireless/realtek/rtw89/chan.c:3194 rtw89_hw_scan_complete drivers/net/wireless/realtek/rtw89/fw.c:8012 rtw89_mac_c2h_scanofld_rsp drivers/net/wireless/realtek/rtw89/mac.c:5059 rtw89_fw_c2h_work drivers/net/wireless/realtek/rtw89/fw.c:6758 process_one_work kernel/workqueue.c:3241 worker_thread kernel/workqueue.c:3400 kthread kernel/kthread.c:463 ret_from_fork arch/x86/kernel/process.c:154 ret_from_fork_asm arch/x86/entry/entry_64.S:258

freed by task 1045 on cpu 9 at 77869.168393s (0.001557s ago): ieee80211_tx_status_skb net/mac80211/status.c:1117 rtw89_pci_release_txwd_skb drivers/net/wireless/realtek/rtw89/pci.c:564 rtw89_pci_release_tx_skbs.isra.0 drivers/net/wireless/realtek/rtw89/pci.c:651 rtw89_pci_release_tx drivers/net/wireless/realtek/rtw89/pci.c:676 rtw89_pci_napi_poll drivers/net/wireless/realtek/rtw89/pci.c:4238 __napi_poll net/core/dev.c:7495 net_rx_action net/core/dev.c:7557 net/core/dev.c:7684 handle_softirqs kernel/softirq.c:580 do_softirq.part.0 kernel/softirq.c:480 __local_bh_enable_ip kernel/softirq.c:407 rtw89_pci_interrupt_threadfn drivers/net/wireless/realtek/rtw89/pci.c:927 irq_thread_fn kernel/irq/manage.c:1133 irq_thread kernel/irq/manage.c:1257 kthread kernel/kthread.c:463 ret_from_fork arch/x86/kernel/process.c:154 ret_from_fork_asm arch/x86/entry/entry_64.S:258

It is a consequence of a race between the waiting and the signaling side of the completion:

Waiting thread Completing thread

rtw89_core_tx_kick_off_and_wait() rcu_assign_pointer(skb_data->wait, wait) /* start waiting */ wait_for_completion_timeout() rtw89_pci_tx_status() rtw89_core_tx_wait_complete() rcu_read_lock() /* signals completion and

---truncated---

AnalysisAI

A use-after-free write in the Linux kernel's Realtek rtw89 Wi-Fi driver lets kernel memory be corrupted when rtw89_core_tx_kick_off_and_wait() races with the TX-completion/status path (rtw89_pci_release_txwd_skb) and dereferences an skb_data buffer that was already freed back to skbuff_head_cache. The flaw was caught by KFENCE during Wi-Fi scan completion and is triggered by a timing race between the waiting and signaling sides of a completion object, affecting systems using Realtek rtw89-supported chipsets. There is no public exploit identified at time of analysis, it is not in CISA KEV, and the EPSS probability is low (0.19%, 9th percentile); the fix has been merged upstream.

Technical ContextAI

The bug lives in drivers/net/wireless/realtek/rtw89/core.c and the PCI TX path (pci.c). rtw89 is the mainline Linux driver for Realtek 802.11ax (Wi-Fi 6/6E) devices such as the RTL8852/8922 family. The root cause is a classic CWE-416 use-after-free stemming from a completion-synchronization race: the waiting thread publishes a wait pointer into skb_data via rcu_assign_pointer() and blocks in wait_for_completion_timeout(), while the completing thread (invoked from NAPI poll / rtw89_pci_tx_status → rtw89_core_tx_wait_complete) signals completion and the mac80211 layer frees the skb via ieee80211_tx_status_skb(). Because the freeing of the skb (allocated by ieee80211_nullfunc_get during rtw89_core_send_nullfunc at scan complete) and the post-wait write to skb_data are not properly ordered, the waiting side writes into memory already returned to the slab allocator. The CWE was reported as N/A by the source but the KFENCE trace unambiguously identifies a use-after-free write.

Affected ProductsAI

The Linux kernel is affected in the Realtek rtw89 wireless driver (drivers/net/wireless/realtek/rtw89/), which supports Realtek Wi-Fi 6/6E chipsets (e.g., RTL8852/8922 series). The reproduction was on kernel 6.17.0-rc1+, and the fix has been backported to multiple stable branches as indicated by the four git.kernel.org stable commits. No precise CPE strings or exact affected version ranges were provided in the input; affected versions are those shipping the rtw89 completion/TX-status code prior to these commits. Vendor references: the stable-tree fix commits at https://git.kernel.org/stable/c/3e31a6bc07312b448fad3b45de578471f86f0e77, https://git.kernel.org/stable/c/895cccf639ac015f3d5f993218cf098db82ac145, https://git.kernel.org/stable/c/bdb3c41b358cf87d99e39d393e164f9e4a6088e6, and https://git.kernel.org/stable/c/f21f530b03b4b23448edb531a0cfea434cb76bb4.

RemediationAI

Update to a Linux kernel build that incorporates the upstream rtw89 fix - Upstream fix available (PR/commit); released patched version not independently confirmed, so identify the stable release corresponding to your kernel series from the four commits (3e31a6bc, 895cccf6, bdb3c41b, f21f530b at git.kernel.org/stable) and apply your distribution's kernel update once it ships these. The four separate stable commits indicate backports across multiple maintained branches, so pull the one matching your series. If you cannot patch immediately and do not use Realtek rtw89 hardware, the driver is not loaded and you are unaffected; where the hardware is present, a practical compensating control is to unload/blacklist the rtw89 modules (e.g., rtw89_pci/rtw89_core) or disable the Wi-Fi interface - the trade-off is loss of wireless connectivity on that adapter. Reducing scan frequency does not reliably eliminate the race and is not a dependable mitigation.

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
Container suse/hpc/warewulf4-x86_64/sle-hpc-node:15.6.17.8.134 Image SLES15-SP6 Image SLES15-SP6-BYOS Image SLES15-SP6-BYOS-Azure Image SLES15-SP6-BYOS-EC2 Image SLES15-SP6-BYOS-GCE Image SLES15-SP6-CHOST-BYOS Image SLES15-SP6-CHOST-BYOS-Aliyun Image SLES15-SP6-CHOST-BYOS-Azure Image SLES15-SP6-CHOST-BYOS-EC2 Image SLES15-SP6-CHOST-BYOS-GCE Image SLES15-SP6-CHOST-BYOS-GDC Image SLES15-SP6-CHOST-BYOS-SAP-CCloud Image SLES15-SP6-EC2 Image SLES15-SP6-EC2-ECS-HVM Image SLES15-SP6-GCE Image SLES15-SP6-HPC-BYOS Image SLES15-SP6-HPC-BYOS-Azure Image SLES15-SP6-HPC-BYOS-EC2 Image SLES15-SP6-HPC-BYOS-GCE Image SLES15-SP6-HPC-EC2 Image SLES15-SP6-HPC-GCE Image SLES15-SP6-Hardened-BYOS Image SLES15-SP6-Hardened-BYOS-Azure Image SLES15-SP6-Hardened-BYOS-EC2 Image SLES15-SP6-Hardened-BYOS-GCE Image SLES15-SP6-SAP Image SLES15-SP6-SAP-Azure Image SLES15-SP6-SAP-EC2 Image SLES15-SP6-SAP-GCE Image SLES15-SP6-SAPCAL Image SLES15-SP6-SAPCAL-Azure Image SLES15-SP6-SAPCAL-EC2 Image SLES15-SP6-SAPCAL-GCE Affected
Container suse/sl-micro/6.0/baremetal-os-container:latest Container suse/sl-micro/6.0/toolbox:latest Affected
Container suse/sl-micro/6.0/base-os-container:2.1.3-7.65 Image SLE-Micro Image SLE-Micro-Azure Image SLE-Micro-BYOS Image SLE-Micro-BYOS-Azure Image SLE-Micro-BYOS-EC2 Image SLE-Micro-BYOS-GCE Image SLE-Micro-EC2 Image SLE-Micro-GCE Affected
Container suse/sl-micro/6.0/kvm-os-container:2.1.3-6.88 Affected
Container suse/sl-micro/6.0/rt-os-container:2.1.3-7.105 Affected

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CVE-2025-40000 vulnerability details – vuln.today
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