CVE-2026-64479 (GCVE-0-2026-64479)
Vulnerability from cvelistv5
Published
2026-07-25 08:51
Modified
2026-08-17 04:56
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
Impacted products
Vendor Product Version
Linux Linux Version: 6389f2c135311c4ce7c08c3b29145c8f95aacf1f
Version: d7e2ce72833bb23a82b4201fbed7214cc04a4a8c
Version: 46397622a3fa8372b8fda0f04b33d16923b03b1b
Version: 46397622a3fa8372b8fda0f04b33d16923b03b1b
Version: 46397622a3fa8372b8fda0f04b33d16923b03b1b
Version: 46397622a3fa8372b8fda0f04b33d16923b03b1b
Version: 46397622a3fa8372b8fda0f04b33d16923b03b1b
 Create a notification for this product.
Show details on NVD website

To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "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",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.145",
                  "versionStartIncluding": "6.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.96",
                  "versionStartIncluding": "6.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.39",
                  "versionStartIncluding": "6.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.4",
                  "versionStartIncluding": "6.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "6.5",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "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."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:56:25.868Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/d7649aa11089a93ea2285c210397aa67e5800766"
        },
        {
          "url": "https://git.kernel.org/stable/c/a224c84e5d3d35708c082c84ad12d81d90762195"
        },
        {
          "url": "https://git.kernel.org/stable/c/ea672a9f6cc38f06fe69dd2c257ef8a3d4db179a"
        },
        {
          "url": "https://git.kernel.org/stable/c/fb1aa5082847b98f44f9c6272aee9d0dca9244f0"
        },
        {
          "url": "https://git.kernel.org/stable/c/651ba82fe2a144bc7356d940bfd235c3810b0549"
        },
        {
          "url": "https://git.kernel.org/stable/c/6ded42615fa1f4949925afd0a8a9e1ab3bf96202"
        },
        {
          "url": "https://git.kernel.org/stable/c/435990e25bf1f4af3e6df12a6fbfd1f7ba4a97d4"
        }
      ],
      "title": "ALSA: seq: Fix uninitialised heap leak in snd_seq_event_dup()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64479",
    "datePublished": "2026-07-25T08:51:41.006Z",
    "dateReserved": "2026-07-19T15:36:31.791Z",
    "dateUpdated": "2026-08-17T04:56:25.868Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.