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CVE-2026-43427: usb: class: cdc-wdm: fix reordering issue in read code path

• Severity: high (CVSS 7.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-08 · updated 2026-06-17
• Weakness: CWE-125

Description

In the Linux kernel, the following vulnerability has been resolved: usb: class: cdc-wdm: fix reordering issue in read code path Quoting the bug report: Due to compiler optimization or CPU out-of-order execution, the desc->length update can be reordered before the memmove. If this happens, wdm_read() can see the new length and call copy_to_user() on uninitialized memory. This also violates LKMM data race rules [1]. Fix it by using WRITE_ONCE and memory barriers.

Affected products

• Linux kernel: from 2.6.26.1 before 5.10.253; from 5.11 before 5.15.203; from 5.16 before 6.1.167; from 6.2 before 6.6.130; from 6.7 before 6.12.78; from 6.13 before 6.18.19 — fixed in 5.10.253, 5.15.203, 6.1.167, 6.12.78, 6.18.19, 6.19.9

How to fix

Upgrade to a fixed version: Linux kernel 5.10.253, 5.15.203, 6.1.167, 6.12.78. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/170e8daca24da6edb4be82ab01abf44e87af387b
• https://git.kernel.org/stable/c/276aef0fd2b92f41b920ac891c72cadeee957934
• https://git.kernel.org/stable/c/4ee3062bf2c9a722afef429826e8607eaf3fc6a0
• https://git.kernel.org/stable/c/638328ca9c17ae6511ad62198c57bae32ffa3c91
• https://git.kernel.org/stable/c/67ed312124bb1b61858778ac0b985b48961c862a
• https://git.kernel.org/stable/c/8df672bfe3ec2268c2636584202755898e547173
• https://git.kernel.org/stable/c/c8fa96ed021923dae147bcd9f9205b8df7b82360
• https://git.kernel.org/stable/c/e3c874b05901dc519054b5107d16620e6d2b5fea

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