{"id":"CVE-2026-64479","summary":"ALSA: seq: Fix uninitialised heap leak in snd_seq_event_dup()","details":"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(&cell-\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.","modified":"2026-07-27T04:03:22.310205175Z","published":"2026-07-25T08:51:41.006Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64479.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/435990e25bf1f4af3e6df12a6fbfd1f7ba4a97d4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/651ba82fe2a144bc7356d940bfd235c3810b0549"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6ded42615fa1f4949925afd0a8a9e1ab3bf96202"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a224c84e5d3d35708c082c84ad12d81d90762195"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d7649aa11089a93ea2285c210397aa67e5800766"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ea672a9f6cc38f06fe69dd2c257ef8a3d4db179a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/fb1aa5082847b98f44f9c6272aee9d0dca9244f0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64479.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64479"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6389f2c135311c4ce7c08c3b29145c8f95aacf1f"},{"fixed":"d7649aa11089a93ea2285c210397aa67e5800766"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"d7e2ce72833bb23a82b4201fbed7214cc04a4a8c"},{"fixed":"a224c84e5d3d35708c082c84ad12d81d90762195"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"46397622a3fa8372b8fda0f04b33d16923b03b1b"},{"fixed":"ea672a9f6cc38f06fe69dd2c257ef8a3d4db179a"},{"fixed":"fb1aa5082847b98f44f9c6272aee9d0dca9244f0"},{"fixed":"651ba82fe2a144bc7356d940bfd235c3810b0549"},{"fixed":"6ded42615fa1f4949925afd0a8a9e1ab3bf96202"},{"fixed":"435990e25bf1f4af3e6df12a6fbfd1f7ba4a97d4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64479.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.5.0"},{"fixed":"6.6.145"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.96"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.39"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64479.json"}}],"schema_version":"1.7.5"}