{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-98116", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:25:14.317Z", "datePublished": "2026-09-25T10:36:01.723Z", "dateUpdated": "2026-09-25T14:42:08.633Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-09-25T14:42:08.633Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: pcm: Serialize PCM mmap with buffer reallocation to fix page UAF\n\nsnd_pcm_hw_params() and snd_pcm_hw_free() guard buffer reallocation\nwith an mmap_count check performed under the PCM stream lock, but the\nlock is released long before the buffer is actually freed:\nsnd_pcm_sync_stop(), constraint refinement and do_free_pages() all\nhappen in between. snd_pcm_mmap_data(), on the other hand, takes no\nlock at all: it validates against the old buffer's state and\ndma_bytes, remaps its pages into the VMA, and only then increments\nmmap_count.\n\nA concurrent mmap() can therefore slip in between the check and the\nfree. remap_pfn_range() installs writable PTEs for the old buffer's\npages without taking page references, and the subsequent\ndo_free_pages() returns those pages to the page allocator while the\nVMA still maps them. This leaves a stale, writable mapping of freed\npages: a page-level use-after-free that can be leveraged for local\nprivilege escalation.\n\nMake snd_pcm_mmap_data() participate in the buffer-access scheme\nintroduced for hw_params/hw_free: acquire runtime->buffer_accessing\nbefore validating and remapping, and release it afterwards. Buffer\nreallocation already fails with -EBUSY while accessors are active,\nand the mmap side now fails with -EBUSY while a reallocation is in\nprogress, so the validate/remap sequence and the check/free sequence\ncan no longer interleave.\n\nA reproducer that turns this race into a stale writable mapping of\nthe freed DMA buffer pages is available on request." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The bug is triggered by mmap() on a local /dev/snd/pcmC*D* file descriptor (snd_pcm_mmap -> snd_pcm_mmap_data) racing with SNDRV_PCM_IOCTL_HW_PARAMS/HW_FREE ioctls on the same fd. No remote protocol carries any of the inputs.\nAC:L - One process controls both sides of the race: one thread calls mmap() and another calls hw_free/hw_params. The window runs from the mmap_count check under the stream lock through snd_pcm_sync_stop and refinement to do_free_pages, and the attacker can retry as often as needed.\nPR:L - Opening the PCM device node takes ordinary local user access, either the audio group or the udev uaccess ACL given to the logged-in seat user. No capability is checked on the mmap or hw_params/hw_free paths.\nUI:N - The attacker opens the device, sets hw_params and races the mmap against hw_free entirely through their own syscalls. No other user has to do anything.\nS:U - This is a local kernel privilege escalation within the same kernel security authority. It crosses no VM or IOMMU boundary.\nC:H - remap_pfn_range installs PTEs for the old DMA buffer pages without taking page references, and do_free_pages then frees them. The attacker keeps a direct mapping of whatever the page allocator reuses those pages for, such as page tables, cred or slab pages, and can read it.\nI:H - The stale mapping of the freed buffer pages is writable, which gives direct write access to reallocated kernel pages. This is a page-level UAF that enables privilege escalation, as the fix commit itself states.\nA:H - Writing through the stale PTEs into pages that have been reallocated corrupts arbitrary kernel memory, which leads to oopses, panics or page-state BUGs." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "sound/core/pcm_native.c" ], "versions": [ { "version": "92ee3c60ec9fe64404dc035e7c41277d74aa26cb", "lessThan": "cbc7ec97601d09b74e05e44470fa6b0bcdabf3f5", "status": "affected", "versionType": "git" }, { "version": "92ee3c60ec9fe64404dc035e7c41277d74aa26cb", "lessThan": "fd137bf8149bc6460f9b7b1fc292025da04cb9ee", "status": "affected", "versionType": "git" }, { "version": "92ee3c60ec9fe64404dc035e7c41277d74aa26cb", "lessThan": "8c1882dfee8f404d118020664b73eb4592172226", "status": "affected", "versionType": "git" }, { "version": "92ee3c60ec9fe64404dc035e7c41277d74aa26cb", "lessThan": "9b110a9dcecc59516c77cb3c0caf1f492f75df2d", "status": "affected", "versionType": "git" }, { "version": "a42aa926843acca96c0dfbde2e835b8137f2f092", "status": "affected", "versionType": "git" }, { "version": "9cb6c40a6ebe4a0cfc9d6a181958211682cffea9", "status": "affected", "versionType": "git" }, { "version": "fbeb492694ce0441053de57699e1e2b7bc148a69", "status": "affected", "versionType": "git" }, { "version": "0f6947f5f5208f6ebd4d76a82a4757e2839a23f8", "status": "affected", "versionType": "git" }, { "version": "33061d0fba51d2bf70a2ef9645f703c33fe8e438", "status": "affected", "versionType": "git" }, { "version": "0090c13cbbdffd7da079ac56f80373a9a1be0bf8", "status": "affected", "versionType": "git" }, { "version": "1bbf82d9f961414d6c76a08f7f843ea068e0ab7b", "status": "affected", "versionType": "git" }, { "version": "4.14.279", "lessThan": "4.15", "status": "affected", "versionType": "semver" }, { "version": "4.19.243", "lessThan": "4.20", "status": "affected", "versionType": "semver" }, { "version": "5.4.193", "lessThan": "5.5", "status": "affected", "versionType": "semver" }, { "version": "5.10.109", "lessThan": "5.11", "status": "affected", "versionType": "semver" }, { "version": "5.15.32", "lessThan": "5.16", "status": "affected", "versionType": "semver" }, { "version": "5.16.18", "lessThan": "5.17", "status": "affected", "versionType": "semver" }, { "version": "5.17.1", "lessThan": "5.18", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "sound/core/pcm_native.c" ], "versions": [ { "version": "5.18", "status": "affected" }, { "version": "0", "lessThan": "5.18", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.111", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.53", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.7", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3-rc2", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "6.12.111" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "6.18.53" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "7.2.7" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "7.3-rc2" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.14.279" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.19.243" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.4.193" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10.109" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15.32" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.16.18" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.17.1" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/cbc7ec97601d09b74e05e44470fa6b0bcdabf3f5" }, { "url": "https://git.kernel.org/stable/c/fd137bf8149bc6460f9b7b1fc292025da04cb9ee" }, { "url": "https://git.kernel.org/stable/c/8c1882dfee8f404d118020664b73eb4592172226" }, { "url": "https://git.kernel.org/stable/c/9b110a9dcecc59516c77cb3c0caf1f492f75df2d" } ], "title": "ALSA: pcm: Serialize PCM mmap with buffer reallocation to fix page UAF", "x_generator": { "engine": "bippy-1.2.0" } } } }