FKIE_CVE-2026-64479

Vulnerability from fkie_nvd - Published: 2026-07-25 10:17 - Updated: 2026-07-25 10:17
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: ALSA: seq: Fix uninitialised heap leak in snd_seq_event_dup() snd_seq_event_dup() copies an incoming event into a pool cell and, in the UMP-enabled build, clears the trailing cell->ump.raw.extra word that the memcpy() did not cover. The guard deciding whether to clear it compares the copied size against sizeof(cell->event): memcpy(&cell->ump, event, size); if (size < sizeof(cell->event)) cell->ump.raw.extra = 0; For a legacy (non-UMP) event, size == sizeof(struct snd_seq_event) == sizeof(cell->event), so the condition is false and the extra word keeps stale data. The cell pool is allocated with kvmalloc() (not zeroed) and cells are reused via a free list, so that word holds uninitialised heap or leftover event data. When such a cell is delivered to a UMP client (client->midi_version > 0) that set SNDRV_SEQ_FILTER_NO_CONVERT -- so the legacy event reaches it unconverted -- snd_seq_read() reads it out as the larger struct snd_seq_ump_event and copies the stale word to user space, a 4-byte kernel heap infoleak to an unprivileged /dev/snd/seq client. Compare against sizeof(cell->ump) instead, so the trailing word is zeroed for every event shorter than the UMP cell.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/435990e25bf1f4af3e6df12a6fbfd1f7ba4a97d4
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/651ba82fe2a144bc7356d940bfd235c3810b0549
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6ded42615fa1f4949925afd0a8a9e1ab3bf96202
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a224c84e5d3d35708c082c84ad12d81d90762195
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d7649aa11089a93ea2285c210397aa67e5800766
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/ea672a9f6cc38f06fe69dd2c257ef8a3d4db179a
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/fb1aa5082847b98f44f9c6272aee9d0dca9244f0
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "sound/core/seq/seq_memory.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "d7649aa11089a93ea2285c210397aa67e5800766",
              "status": "affected",
              "version": "6389f2c135311c4ce7c08c3b29145c8f95aacf1f",
              "versionType": "git"
            },
            {
              "lessThan": "a224c84e5d3d35708c082c84ad12d81d90762195",
              "status": "affected",
              "version": "d7e2ce72833bb23a82b4201fbed7214cc04a4a8c",
              "versionType": "git"
            },
            {
              "lessThan": "ea672a9f6cc38f06fe69dd2c257ef8a3d4db179a",
              "status": "affected",
              "version": "46397622a3fa8372b8fda0f04b33d16923b03b1b",
              "versionType": "git"
            },
            {
              "lessThan": "fb1aa5082847b98f44f9c6272aee9d0dca9244f0",
              "status": "affected",
              "version": "46397622a3fa8372b8fda0f04b33d16923b03b1b",
              "versionType": "git"
            },
            {
              "lessThan": "651ba82fe2a144bc7356d940bfd235c3810b0549",
              "status": "affected",
              "version": "46397622a3fa8372b8fda0f04b33d16923b03b1b",
              "versionType": "git"
            },
            {
              "lessThan": "6ded42615fa1f4949925afd0a8a9e1ab3bf96202",
              "status": "affected",
              "version": "46397622a3fa8372b8fda0f04b33d16923b03b1b",
              "versionType": "git"
            },
            {
              "lessThan": "435990e25bf1f4af3e6df12a6fbfd1f7ba4a97d4",
              "status": "affected",
              "version": "46397622a3fa8372b8fda0f04b33d16923b03b1b",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "sound/core/seq/seq_memory.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.5"
            },
            {
              "lessThan": "6.5",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.145",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.96",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.39",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: seq: Fix uninitialised heap leak in snd_seq_event_dup()\n\nsnd_seq_event_dup() copies an incoming event into a pool cell and, in\nthe UMP-enabled build, clears the trailing cell-\u003eump.raw.extra word that\nthe memcpy() did not cover.  The guard deciding whether to clear it\ncompares the copied size against sizeof(cell-\u003eevent):\n\n\tmemcpy(\u0026cell-\u003eump, event, size);\n\tif (size \u003c sizeof(cell-\u003eevent))\n\t\tcell-\u003eump.raw.extra = 0;\n\nFor a legacy (non-UMP) event, size == sizeof(struct snd_seq_event) ==\nsizeof(cell-\u003eevent), so the condition is false and the extra word keeps\nstale data.  The cell pool is allocated with kvmalloc() (not zeroed) and\ncells are reused via a free list, so that word holds uninitialised heap\nor leftover event data.\n\nWhen such a cell is delivered to a UMP client (client-\u003emidi_version \u003e 0)\nthat set SNDRV_SEQ_FILTER_NO_CONVERT -- so the legacy event reaches it\nunconverted -- snd_seq_read() reads it out as the larger struct\nsnd_seq_ump_event and copies the stale word to user space, a 4-byte\nkernel heap infoleak to an unprivileged /dev/snd/seq client.\n\nCompare against sizeof(cell-\u003eump) instead, so the trailing word is zeroed\nfor every event shorter than the UMP cell."
    }
  ],
  "id": "CVE-2026-64479",
  "lastModified": "2026-07-25T10:17:33.493",
  "metrics": {},
  "published": "2026-07-25T10:17:33.493",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/435990e25bf1f4af3e6df12a6fbfd1f7ba4a97d4"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/651ba82fe2a144bc7356d940bfd235c3810b0549"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6ded42615fa1f4949925afd0a8a9e1ab3bf96202"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a224c84e5d3d35708c082c84ad12d81d90762195"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/d7649aa11089a93ea2285c210397aa67e5800766"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ea672a9f6cc38f06fe69dd2c257ef8a3d4db179a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/fb1aa5082847b98f44f9c6272aee9d0dca9244f0"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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