CVE-2026-98836 (GCVE-0-2026-98836)

Vulnerability from cvelistv5 – Published: 2026-10-18 15:49 – Updated: 2026-10-21 12:57
VLAI
Title
ALSA: line6: reject oversized playback packets
Summary
In the Linux kernel, the following vulnerability has been resolved: ALSA: line6: reject oversized playback packets Each playback URB is handed a slice of out.buffer that is exactly LINE6_ISO_PACKETS * max_packet_size_out bytes, sized from the OUT endpoint, but the number of bytes written into that slice is never compared against it. submit_audio_out_urb() takes the frame count from prev_fsize, which audio_in_callback() derived from the *IN* endpoint's received packet length, and rescales it with the playback frame size; when prev_fsize is still zero it synthesizes a length from the sample rate instead. On a device declaring a large IN wMaxPacketSize and a small OUT wMaxPacketSize, the resulting memcpy(), or the memset() when the playback stream is idle, runs past its slice and, as the reproducer below shows, beyond the allocation. usb_submit_urb() is not a backstop. max_packet_size_out comes from usb_maxpacket(), which returns only the low 11 bits of wMaxPacketSize, while USB core validates a high-speed isochronous length against that base scaled by usb_endpoint_maxp_mult(). A length of up to three times the allocated slice is therefore accepted, and even a rejected URB is only rejected after the write. Reject a packet that does not fit the slice the driver allocated for it. Clamping it instead would silently shorten the capture-derived rate feedback and desynchronize the two streams. BUG: KASAN: slab-out-of-bounds in submit_audio_out_urb (sound/usb/line6/playback.c:229) Write of size 1024 at addr ffff888100bbd400 by task kworker/1:2/5002 Workqueue: events line6_startup_work Call Trace: __asan_memcpy (mm/kasan/shadow.c:106) submit_audio_out_urb (sound/usb/line6/playback.c:229) line6_submit_audio_out_all_urbs (sound/usb/line6/playback.c:291) line6_stream_start (sound/usb/line6/pcm.c:194) line6_pcm_acquire (sound/usb/line6/pcm.c:337) line6_startup_work (sound/usb/line6/driver.c:728) process_one_work (kernel/workqueue.c:3396) worker_thread (kernel/workqueue.c:3479 kernel/workqueue.c:3560) kthread (kernel/kthread.c:436) ret_from_fork (arch/x86/kernel/process.c:158) ret_from_fork_asm (arch/x86/entry/entry_64.S:245) The buggy address belongs to the object at ffff888100bbd400 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 0 bytes inside of allocated 256-byte region [ffff888100bbd400, ffff888100bbd500)
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7056 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 7a0f55aeeb8f1fa32a119d34ddfefc6100936692 , < 933d8ac23388eb208ea195231d682dce0bec86ca (git)
Affected: 7a0f55aeeb8f1fa32a119d34ddfefc6100936692 , < a84371be89c39ccc46c7af8b9eb15c448df9265f (git)
Affected: 7a0f55aeeb8f1fa32a119d34ddfefc6100936692 , < 3f75da1e4ee699f6650d23d6897cf443b01856c7 (git)
Affected: 7a0f55aeeb8f1fa32a119d34ddfefc6100936692 , < b78748424f29f07d310484b2b36afdececa74389 (git)
Affected: 7a0f55aeeb8f1fa32a119d34ddfefc6100936692 , < 61b0a5a114fa4552892da5c0ff2f42e63bf08c6b (git)
guessed Create a notification for this product.
Linux Linux Affected: 4.9
Unaffected: 0 , < 4.9 (semver)
Unaffected: 6.6.160 , ≤ 6.6.* (semver)
Unaffected: 6.12.113 , ≤ 6.12.* (semver)
Unaffected: 6.18.56 , ≤ 6.18.* (semver)
Unaffected: 7.2.10 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: line6: reject oversized playback packets\n\nEach playback URB is handed a slice of out.buffer that is exactly\nLINE6_ISO_PACKETS * max_packet_size_out bytes, sized from the OUT\nendpoint, but the number of bytes written into that slice is never\ncompared against it.\n\nsubmit_audio_out_urb() takes the frame count from prev_fsize, which\naudio_in_callback() derived from the *IN* endpoint\u0027s received packet\nlength, and rescales it with the playback frame size; when prev_fsize is\nstill zero it synthesizes a length from the sample rate instead.  On a\ndevice declaring a large IN wMaxPacketSize and a small OUT\nwMaxPacketSize, the resulting memcpy(), or the memset() when the\nplayback stream is idle, runs past its slice and, as the reproducer\nbelow shows, beyond the allocation.\n\nusb_submit_urb() is not a backstop.  max_packet_size_out comes from\nusb_maxpacket(), which returns only the low 11 bits of wMaxPacketSize,\nwhile USB core validates a high-speed isochronous length against that\nbase scaled by usb_endpoint_maxp_mult().  A length of up to three times\nthe allocated slice is therefore accepted, and even a rejected URB is\nonly rejected after the write.\n\nReject a packet that does not fit the slice the driver allocated for it.\nClamping it instead would silently shorten the capture-derived rate\nfeedback and desynchronize the two streams.\n\n  BUG: KASAN: slab-out-of-bounds in submit_audio_out_urb (sound/usb/line6/playback.c:229)\n  Write of size 1024 at addr ffff888100bbd400 by task kworker/1:2/5002\n  Workqueue: events line6_startup_work\n  Call Trace:\n   __asan_memcpy (mm/kasan/shadow.c:106)\n   submit_audio_out_urb (sound/usb/line6/playback.c:229)\n   line6_submit_audio_out_all_urbs (sound/usb/line6/playback.c:291)\n   line6_stream_start (sound/usb/line6/pcm.c:194)\n   line6_pcm_acquire (sound/usb/line6/pcm.c:337)\n   line6_startup_work (sound/usb/line6/driver.c:728)\n   process_one_work (kernel/workqueue.c:3396)\n   worker_thread (kernel/workqueue.c:3479 kernel/workqueue.c:3560)\n   kthread (kernel/kthread.c:436)\n   ret_from_fork (arch/x86/kernel/process.c:158)\n   ret_from_fork_asm (arch/x86/entry/entry_64.S:245)\n\n  The buggy address belongs to the object at ffff888100bbd400\n   which belongs to the cache kmalloc-256 of size 256\n  The buggy address is located 0 bytes inside of\n   allocated 256-byte region [ffff888100bbd400, ffff888100bbd500)"
        }
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      "providerMetadata": {
        "dateUpdated": "2026-10-21T12:57:22.028Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        {
          "url": "https://git.kernel.org/stable/c/61b0a5a114fa4552892da5c0ff2f42e63bf08c6b"
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      "title": "ALSA: line6: reject oversized playback packets",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98836",
    "datePublished": "2026-10-18T15:49:51.823Z",
    "dateReserved": "2026-09-25T10:25:14.372Z",
    "dateUpdated": "2026-10-21T12:57:22.028Z",
    "state": "PUBLISHED"
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      "id": "msrc_CVE-2026-98836",
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      "product_status:known_affected": "1",
      "product_status:under_investigation": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "ALSA: line6: reject oversized playback packets",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-98836.json",
      "version": "2"
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        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: line6: reject oversized playback packets\n\nEach playback URB is handed a slice of out.buffer that is exactly\nLINE6_ISO_PACKETS * max_packet_size_out bytes, sized from the OUT\nendpoint, but the number of bytes written into that slice is never\ncompared against it.\n\nsubmit_audio_out_urb() takes the frame count from prev_fsize, which\naudio_in_callback() derived from the *IN* endpoint\u0027s received packet\nlength, and rescales it with the playback frame size; when prev_fsize is\nstill zero it synthesizes a length from the sample rate instead.  On a\ndevice declaring a large IN wMaxPacketSize and a small OUT\nwMaxPacketSize, the resulting memcpy(), or the memset() when the\nplayback stream is idle, runs past its slice and, as the reproducer\nbelow shows, beyond the allocation.\n\nusb_submit_urb() is not a backstop.  max_packet_size_out comes from\nusb_maxpacket(), which returns only the low 11 bits of wMaxPacketSize,\nwhile USB core validates a high-speed isochronous length against that\nbase scaled by usb_endpoint_maxp_mult().  A length of up to three times\nthe allocated slice is therefore accepted, and even a rejected URB is\nonly rejected after the write.\n\nReject a packet that does not fit the slice the driver allocated for it.\nClamping it instead would silently shorten the capture-derived rate\nfeedback and desynchronize the two streams.\n\n  BUG: KASAN: slab-out-of-bounds in submit_audio_out_urb (sound/usb/line6/playback.c:229)\n  Write of size 1024 at addr ffff888100bbd400 by task kworker/1:2/5002\n  Workqueue: events line6_startup_work\n  Call Trace:\n   __asan_memcpy (mm/kasan/shadow.c:106)\n   submit_audio_out_urb (sound/usb/line6/playback.c:229)\n   line6_submit_audio_out_all_urbs (sound/usb/line6/playback.c:291)\n   line6_stream_start (sound/usb/line6/pcm.c:194)\n   line6_pcm_acquire (sound/usb/line6/pcm.c:337)\n   line6_startup_work (sound/usb/line6/driver.c:728)\n   process_one_work (kernel/workqueue.c:3396)\n   worker_thread (kernel/workqueue.c:3479 kernel/workqueue.c:3560)\n   kthread (kernel/kthread.c:436)\n   ret_from_fork (arch/x86/kernel/process.c:158)\n   ret_from_fork_asm (arch/x86/entry/entry_64.S:245)\n\n  The buggy address belongs to the object at ffff888100bbd400\n   which belongs to the cache kmalloc-256 of size 256\n  The buggy address is located 0 bytes inside of\n   allocated 256-byte region [ffff888100bbd400, ffff888100bbd500)"
          }
        ],
        "id": "CVE-2026-98836",
        "lastModified": "2026-10-21T13:21:48.733",
        "metrics": {},
        "published": "2026-10-18T16:17:37.830",
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        "vulnStatus": "Received"
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-10-23T21:44:53+00:00",
      "cve": "CVE-2026-98836",
      "id": "CVE-2026-98836",
      "initial_release_date": "2026-10-18T00:00:00+00:00",
      "product_status:known_affected": "264",
      "product_status:known_not_affected": "14",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ALSA: line6: reject oversized playback packets",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98836.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "not set",
      "current_release_date": "2026-10-18T23:41:38Z",
      "cve": "CVE-2026-98836",
      "id": "CVE-2026-98836",
      "initial_release_date": "2026-10-18T23:41:38Z",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-98836",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/2026/cve-2026-98836.json",
      "version": "2"
    }
  }
}



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