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CVE-2026-64345: usb: gadget: f_printer: take kref only for successful open

• Severity: medium (CVSS 5.5 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: 2026-07-25 · updated 2026-10-30

Description

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_printer: take kref only for successful open printer_open() returns -EBUSY when the character device is already open, but it increments dev->kref regardless of the return value. VFS does not call ->release() for a failed open, so every rejected second open permanently leaks one reference. Move kref_get() into the successful-open branch.

Affected products

• Linux kernel: from 4.4.241 before 4.5; from 4.9.241 before 4.10; from 4.14.203 before 4.15; from 4.19.154 before 4.20; from 5.4.73 before 5.5; from 5.8.17 before 5.9 — fixed in 4.5, 4.10, 4.15, 4.20, 5.5, 5.9
• Linux: from 4.4.241 before 4.5; from 4.9.241 before 4.10; from 4.14.203 before 4.15; from 4.19.154 before 4.20; from 5.4.73 before 5.5; from 5.8.17 before 5.9 — fixed in 4.5, 4.10, 4.15, 4.20, 5.5, 5.9

How to fix

Upgrade to a fixed version: Linux kernel 4.5, 4.10, 4.15, 4.20; Linux 4.5, 4.10, 4.15, 4.20. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/30adce93d5c4a5a1ec29d9249e3fdfcc391d406b
• https://git.kernel.org/stable/c/75c0ad13e136961328253742501b4efc3988a587
• https://git.kernel.org/stable/c/7f1f24c367938c5537e2308bf9a965f051d14774
• https://git.kernel.org/stable/c/8a5eba992c862b0c94411eecf9b7121e8636db38
• https://git.kernel.org/stable/c/94ec20d97aa51547965a539f660a1fe79c6929a3
• https://git.kernel.org/stable/c/a12d81a9cc2a012a24ecb7f9ba076b9f7c179bd3
• https://git.kernel.org/stable/c/bf20c94fa6aaff945f0ae3a23f3212cd299f28d9

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