{"id":"CVE-2026-64479","title":"ALSA: seq: Fix uninitialised heap leak in snd_seq_event_dup()","summary":"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 t…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 6389f2c135311c4ce7c08c3b29145c8f95aacf1f < d7649aa11089a93ea2285c210397aa67e5800766","Linux >= d7e2ce72833bb23a82b4201fbed7214cc04a4a8c < a224c84e5d3d35708c082c84ad12d81d90762195","Linux >= 46397622a3fa8372b8fda0f04b33d16923b03b1b < ea672a9f6cc38f06fe69dd2c257ef8a3d4db179a","Linux >= 46397622a3fa8372b8fda0f04b33d16923b03b1b < fb1aa5082847b98f44f9c6272aee9d0dca9244f0","Linux >= 46397622a3fa8372b8fda0f04b33d16923b03b1b < 651ba82fe2a144bc7356d940bfd235c3810b0549","Linux >= 46397622a3fa8372b8fda0f04b33d16923b03b1b < 6ded42615fa1f4949925afd0a8a9e1ab3bf96202","Linux >= 46397622a3fa8372b8fda0f04b33d16923b03b1b < 435990e25bf1f4af3e6df12a6fbfd1f7ba4a97d4","Linux 6.5"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-11-06T16:39:55.990458Z"},"published":"2026-07-25","updated":"2026-11-06","sourceUpdated":"2026-11-06T16:44:54.844Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-64479","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"}],"tags":["cve.org"],"epss":0.00181,"epssPercentile":0.07708,"ingestedAt":"2026-11-06T16:57:43.164Z","slug":"CVE-2026-64479","body":"## Overview\n\nIn 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->ump.raw.extra word that\nthe memcpy() did not cover.  The guard deciding whether to clear it\ncompares the copied size against sizeof(cell->event):\n\n\tmemcpy(&cell->ump, event, size);\n\tif (size < sizeof(cell->event))\n\t\tcell->ump.raw.extra = 0;\n\nFor a legacy (non-UMP) event, size == sizeof(struct snd_seq_event) ==\nsizeof(cell->event), 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->midi_version > 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->ump) instead, so the trailing word is zeroed\nfor every event shorter than the UMP cell.\n\n## Affected\n\n- `Linux >= 6389f2c135311c4ce7c08c3b29145c8f95aacf1f < d7649aa11089a93ea2285c210397aa67e5800766`\n- `Linux >= d7e2ce72833bb23a82b4201fbed7214cc04a4a8c < a224c84e5d3d35708c082c84ad12d81d90762195`\n- `Linux >= 46397622a3fa8372b8fda0f04b33d16923b03b1b < ea672a9f6cc38f06fe69dd2c257ef8a3d4db179a`\n- `Linux >= 46397622a3fa8372b8fda0f04b33d16923b03b1b < fb1aa5082847b98f44f9c6272aee9d0dca9244f0`\n- `Linux >= 46397622a3fa8372b8fda0f04b33d16923b03b1b < 651ba82fe2a144bc7356d940bfd235c3810b0549`\n- `Linux >= 46397622a3fa8372b8fda0f04b33d16923b03b1b < 6ded42615fa1f4949925afd0a8a9e1ab3bf96202`\n- `Linux >= 46397622a3fa8372b8fda0f04b33d16923b03b1b < 435990e25bf1f4af3e6df12a6fbfd1f7ba4a97d4`\n- `Linux 6.5`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}