EUVD-2026-38850
GHSA-pjm2-h6fg-mfw7
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Needs local RTL8150 hardware and a tight SMP timing race (AV:L, AC:H, PR:L); main impact is potential crash (A:H) with only marginal freed-memory read (C:L), no integrity impact.
Primary rating from Vendor (Linux).
CVSS VectorVendor: Linux
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
5DescriptionCVE.org
In the Linux kernel, the following vulnerability has been resolved:
net: usb: rtl8150: fix use-after-free in rtl8150_start_xmit()
syzbot reported a KASAN slab-use-after-free read in rtl8150_start_xmit() when accessing skb->len for tx statistics after usb_submit_urb() has been called:
BUG: KASAN: slab-use-after-free in rtl8150_start_xmit+0x71f/0x760 drivers/net/usb/rtl8150.c:712 Read of size 4 at addr ffff88810eb7a930 by task kworker/0:4/5226
The URB completion handler write_bulk_callback() frees the skb via dev_kfree_skb_irq(dev->tx_skb). The URB may complete on another CPU in softirq context before usb_submit_urb() returns in the submitter, so by the time the submitter reads skb->len the skb has already been queued to the per-CPU completion_queue and freed by net_tx_action():
CPU A (xmit) CPU B (USB completion softirq) ------------ ------------------------------ dev->tx_skb = skb; usb_submit_urb() --+
|-------> write_bulk_callback() | dev_kfree_skb_irq(dev->tx_skb) | net_tx_action() | napi_skb_cache_put() <-- free netdev->stats.tx_bytes | += skb->len; <-- UAF read
Fix it by caching skb->len before submitting the URB and using the cached value when updating the tx_bytes counter.
The pre-existing tx_bytes semantics are preserved: the counter tracks the original frame length (skb->len), not the ETH_ZLEN/USB-alignment padded "count" value that is handed to the device. Changing that would be a user-visible accounting change and is out of scope for this UAF fix.
AnalysisAI
Use-after-free in the Linux kernel rtl8150 USB-to-Ethernet driver (drivers/net/usb/rtl8150.c) lets the transmit path read freed socket-buffer memory: rtl8150_start_xmit() reads skb->len for TX byte accounting after usb_submit_urb(), but the URB completion handler write_bulk_callback() can free the skb on another CPU first, producing a slab-use-after-free read flagged by KASAN/syzbot. Affected systems are those using an RTL8150-based USB Ethernet adapter; the practical impact is a stale/garbage stat read or a potential crash from freed-memory access rather than reliable info disclosure. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Requires an RTL8150-based USB-to-Ethernet adapter to be present and bound (driver rtl8150 loaded) on the target, plus active transmission on that interface to drive the TX path. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The published CVSS 3.1 vector AV:N/AC:L/PR:N/UI:N (9.8 Critical) is the inflated auto-assigned score typical of bulk Linux kernel CVEs and does not match the actual mechanics: this is a TX-path race that requires a physically present RTL8150 USB Ethernet adapter and concurrent transmit/completion on an SMP host, which is far from a remote, no-privilege, network-reachable RCE. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | A local attacker (or attacker-controlled malicious USB device) on a host with an RTL8150 USB Ethernet adapter generates rapid outbound traffic to force concurrent rtl8150_start_xmit() submission and write_bulk_callback() completion across CPUs, winning the race so the SKB is freed before skb->len is read. The resulting use-after-free read corrupts/leaks a stats value and, depending on allocator state, can destabilize the kernel; no public exploit code exists and reliable exploitation is impeded by the narrow timing window. |
| Remediation | Vendor-released patch: update to a fixed stable kernel - 6.1.175, 6.6.141, 6.12.91, 6.18.33, 7.0.10, or 7.1 (also 5.10.258, 5.15.209 for older trees) - or apply the corresponding upstream commit (e.g. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: Identify systems running RTL8150 USB Ethernet adapters in your infrastructure (check device inventory or vendor documentation). …
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Same weakness CWE-416 – Use After Free
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External POC / Exploit Code
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