{"id":"CVE-2026-64339","state":"PUBLISHED","title":"usb: misc: usbio: bound bulk IN response length to the received transfer","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nusb: misc: usbio: bound bulk IN response length to the received transfer\n\nusbio_bulk_msg() copies bpkt_len = le16_to_cpu(bpkt->len) bytes out of\nthe bulk IN buffer (usbio->rxbuf, allocated with size usbio->rxbuf_len)\ninto the caller's buffer.  bpkt_len is fully controlled by the device\nand is only checked against ibuf_len; ibuf_len in turn is checked\nagainst usbio->txbuf_len, not against rxbuf_len:\n\n\tif ((obuf_len > (usbio->txbuf_len - sizeof(*bpkt))) ||\n\t    (ibuf_len > (usbio->txbuf_len - sizeof(*bpkt))))\n\t\treturn -EMSGSIZE;\n\ntxbuf_len and rxbuf_len are taken independently from the bulk OUT and\nbulk IN endpoint wMaxPacketSize in usbio_probe().  A malicious or\nmalfunctioning device that advertises a large bulk OUT endpoint and a\nsmall bulk IN endpoint (e.g. by claiming one of the quirk-free IDs such\nas the Lattice NX33U, 0x2ac1:0x20cb) therefore makes ibuf_len, and\nhence the device-supplied bpkt_len, exceed rxbuf_len.  memcpy() then\nreads up to txbuf_len - rxbuf_len bytes past the end of the rxbuf slab\nobject.  The over-read bytes are handed back to the i2c layer and on to\nuser space through i2c-dev, disclosing adjacent slab memory; with KASAN\nthis is reported as a slab-out-of-bounds read.\n\nThe number of bytes actually received is already known: act equals the\nURB actual_length and is bounded by rxbuf_len.  Reject any response\nthat claims more payload than was received, mirroring the existing\n\"act < sizeof(*bpkt)\" check just above.\n\nThe control path (usbio_ctrl_msg()) is not affected: it uses a single\nbuffer (ctrlbuf) for both directions, so its analogous copy can never\nleave the allocation.\n\nFound by code review.  The out-of-bounds read was confirmed under\nAddressSanitizer with a faithful userspace model of usbio_bulk_msg()'s\nreceive path (an rxbuf_len-sized buffer, the same act/ibuf_len/bpkt_len\nchecks and the memcpy).  A USB raw-gadget + dummy_hcd reproducer is\nalso available.","publishedAt":"2026-07-25T08:50:03.272Z","updatedAt":"2026-08-17T04:53:42.778Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"121a0f839dbb397af5fabb701cea3e9983223e50","status":"affected","lessThan":"48394f94211cf8fe0ea8604fc441633abf90fc94","versionType":"git"},{"version":"121a0f839dbb397af5fabb701cea3e9983223e50","status":"affected","lessThan":"fc1b546973c1442d5b947fcdd03581f20ecc5bd2","versionType":"git"},{"version":"121a0f839dbb397af5fabb701cea3e9983223e50","status":"affected","lessThan":"8c6314489550fa81d41723a0ff33f655b5b6c7b6","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/usb/misc/usbio.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.18","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.18","versionType":"semver"},{"version":"6.18.39","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.4","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/usb/misc/usbio.c"]}],"references":["https://git.kernel.org/stable/c/48394f94211cf8fe0ea8604fc441633abf90fc94","https://git.kernel.org/stable/c/fc1b546973c1442d5b947fcdd03581f20ecc5bd2","https://git.kernel.org/stable/c/8c6314489550fa81d41723a0ff33f655b5b6c7b6"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64339.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64339","state":"PUBLISHED","datePublished":"2026-07-25T08:50:03.272Z","dateUpdated":"2026-08-17T04:53:42.778Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T15:36:31.781Z"},"containers":{"cna":{"title":"usb: misc: usbio: bound bulk IN response length to the received transfer","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nusb: misc: usbio: bound bulk IN response length to the received transfer\n\nusbio_bulk_msg() copies bpkt_len = le16_to_cpu(bpkt->len) bytes out of\nthe bulk IN buffer (usbio->rxbuf, allocated with size usbio->rxbuf_len)\ninto the caller's buffer.  bpkt_len is fully controlled by the device\nand is only checked against ibuf_len; ibuf_len in turn is checked\nagainst usbio->txbuf_len, not against rxbuf_len:\n\n\tif ((obuf_len > (usbio->txbuf_len - sizeof(*bpkt))) ||\n\t    (ibuf_len > (usbio->txbuf_len - sizeof(*bpkt))))\n\t\treturn -EMSGSIZE;\n\ntxbuf_len and rxbuf_len are taken independently from the bulk OUT and\nbulk IN endpoint wMaxPacketSize in usbio_probe().  A malicious or\nmalfunctioning device that advertises a large bulk OUT endpoint and a\nsmall bulk IN endpoint (e.g. by claiming one of the quirk-free IDs such\nas the Lattice NX33U, 0x2ac1:0x20cb) therefore makes ibuf_len, and\nhence the device-supplied bpkt_len, exceed rxbuf_len.  memcpy() then\nreads up to txbuf_len - rxbuf_len bytes past the end of the rxbuf slab\nobject.  The over-read bytes are handed back to the i2c layer and on to\nuser space through i2c-dev, disclosing adjacent slab memory; with KASAN\nthis is reported as a slab-out-of-bounds read.\n\nThe number of bytes actually received is already known: act equals the\nURB actual_length and is bounded by rxbuf_len.  Reject any response\nthat claims more payload than was received, mirroring the existing\n\"act < sizeof(*bpkt)\" check just above.\n\nThe control path (usbio_ctrl_msg()) is not affected: it uses a single\nbuffer (ctrlbuf) for both directions, so its analogous copy can never\nleave the allocation.\n\nFound by code review.  The out-of-bounds read was confirmed under\nAddressSanitizer with a faithful userspace model of usbio_bulk_msg()'s\nreceive path (an rxbuf_len-sized buffer, the same act/ibuf_len/bpkt_len\nchecks and the memcpy).  A USB raw-gadget + dummy_hcd reproducer is\nalso available."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"121a0f839dbb397af5fabb701cea3e9983223e50","status":"affected","lessThan":"48394f94211cf8fe0ea8604fc441633abf90fc94","versionType":"git"},{"version":"121a0f839dbb397af5fabb701cea3e9983223e50","status":"affected","lessThan":"fc1b546973c1442d5b947fcdd03581f20ecc5bd2","versionType":"git"},{"version":"121a0f839dbb397af5fabb701cea3e9983223e50","status":"affected","lessThan":"8c6314489550fa81d41723a0ff33f655b5b6c7b6","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/usb/misc/usbio.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.18","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.18","versionType":"semver"},{"version":"6.18.39","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.4","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/usb/misc/usbio.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/48394f94211cf8fe0ea8604fc441633abf90fc94"},{"url":"https://git.kernel.org/stable/c/fc1b546973c1442d5b947fcdd03581f20ecc5bd2"},{"url":"https://git.kernel.org/stable/c/8c6314489550fa81d41723a0ff33f655b5b6c7b6"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T04:53:42.778Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.18","versionEndExcluding":"6.18.39"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.18","versionEndExcluding":"7.1.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.18","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}