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National Vulnerability Database

National Vulnerability Database

NVD

National Vulnerability Database
  1. Vulnerabilities

CVE-2026-64339 Detail

Description

In the Linux kernel, the following vulnerability has been resolved: usb: misc: usbio: bound bulk IN response length to the received transfer usbio_bulk_msg() copies bpkt_len = le16_to_cpu(bpkt->len) bytes out of the bulk IN buffer (usbio->rxbuf, allocated with size usbio->rxbuf_len) into the caller's buffer. bpkt_len is fully controlled by the device and is only checked against ibuf_len; ibuf_len in turn is checked against usbio->txbuf_len, not against rxbuf_len: if ((obuf_len > (usbio->txbuf_len - sizeof(*bpkt))) || (ibuf_len > (usbio->txbuf_len - sizeof(*bpkt)))) return -EMSGSIZE; txbuf_len and rxbuf_len are taken independently from the bulk OUT and bulk IN endpoint wMaxPacketSize in usbio_probe(). A malicious or malfunctioning device that advertises a large bulk OUT endpoint and a small bulk IN endpoint (e.g. by claiming one of the quirk-free IDs such as the Lattice NX33U, 0x2ac1:0x20cb) therefore makes ibuf_len, and hence the device-supplied bpkt_len, exceed rxbuf_len. memcpy() then reads up to txbuf_len - rxbuf_len bytes past the end of the rxbuf slab object. The over-read bytes are handed back to the i2c layer and on to user space through i2c-dev, disclosing adjacent slab memory; with KASAN this is reported as a slab-out-of-bounds read. The number of bytes actually received is already known: act equals the URB actual_length and is bounded by rxbuf_len. Reject any response that claims more payload than was received, mirroring the existing "act < sizeof(*bpkt)" check just above. The control path (usbio_ctrl_msg()) is not affected: it uses a single buffer (ctrlbuf) for both directions, so its analogous copy can never leave the allocation. Found by code review. The out-of-bounds read was confirmed under AddressSanitizer with a faithful userspace model of usbio_bulk_msg()'s receive path (an rxbuf_len-sized buffer, the same act/ibuf_len/bpkt_len checks and the memcpy). A USB raw-gadget + dummy_hcd reproducer is also available.


Metrics

 
NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.
CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

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URL Source(s) Tag(s)
https://git.kernel.org/stable/c/48394f94211cf8fe0ea8604fc441633abf90fc94 kernel.org
https://git.kernel.org/stable/c/8c6314489550fa81d41723a0ff33f655b5b6c7b6 kernel.org
https://git.kernel.org/stable/c/fc1b546973c1442d5b947fcdd03581f20ecc5bd2 kernel.org

Weakness Enumeration

CWE-ID CWE Name Source

Change History

2 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2026-64339
NVD Published Date:
07/25/2026
NVD Last Modified:
08/17/2026
Source:
kernel.org