CVE-2026-98116ALSA: pcm: Serialize PCM mmap with buffer reallocation to fix page UAF
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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In the Linux kernel, the following vulnerability has been resolved: ALSA: pcm: Serialize PCM mmap with buffer reallocation to fix page UAF snd_pcm_hw_params() and snd_pcm_hw_free() guard buffer reallocation with an mmap_count check performed under the PCM stream lock, but the lock is released long before the buffer is actually freed: snd_pcm_sync_stop(), constraint refinement and do_free_pages() all happen in between. snd_pcm_mmap_data(), on the other hand, takes no lock at all: it validates against the old buffer's state and dma_bytes, remaps its pages into the VMA, and only then increments mmap_count. A concurrent mmap() can therefore slip in between the check and the free. remap_pfn_range() installs writable PTEs for the old buffer's pages without taking page references, and the subsequent do_free_pages() returns those pages to the page allocator while the VMA still maps them. This leaves a stale, writable mapping of freed pages: a page-level use-after-free that can be leveraged for local privilege escalation. Make snd_pcm_mmap_data() participate in the buffer-access scheme introduced for hw_params/hw_free: acquire runtime->buffer_accessing before validating and remapping, and release it afterwards. Buffer reallocation already fails with -EBUSY while accessors are active, and the mmap side now fails with -EBUSY while a reallocation is in progress, so the validate/remap sequence and the check/free sequence can no longer interleave. A reproducer that turns this race into a stale writable mapping of the freed DMA buffer pages is available on request.
- CVSS
- 7.8 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Undergoing Analysis
- Record last updated
- Oct 3, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from 33061d0fba51d2bf70a2ef9645f703c33fe8e438 before e6cdd2a0470d64073349a970dc1691433804b271; from 92ee3c60ec9fe64404dc035e7c41277d74aa26cb before 9857a75714bb5df4781e4d8b1a1753b1e17bf07a; from 92ee3c60ec9fe64404dc035e7c41277d74aa26cb before cbadf2575d25e7dcc0d4da2717817ae569fbc99b; from 92ee3c60ec9fe64404dc035e7c41277d74aa26cb before cbc7ec97601d09b74e05e44470fa6b0bcdabf3f5; from 92ee3c60ec9fe64404dc035e7c41277d74aa26cb before fd137bf8149bc6460f9b7b1fc292025da04cb9ee; 92ee3c60ec9fe64404dc035e7c41277d74aa26cb builds before 8c1882dfee8f404d118020664b73eb4592172226; 92ee3c60ec9fe64404dc035e7c41277d74aa26cb builds before 9b110a9dcecc59516c77cb3c0caf1f492f75df2d; a42aa926843acca96c0dfbde2e835b8137f2f092; and 12 more ranges | CNA record |
References
- https://git.kernel.org/stable/c/e6cdd2a0470d64073349a970dc1691433804b271
- https://git.kernel.org/stable/c/9857a75714bb5df4781e4d8b1a1753b1e17bf07a
- https://git.kernel.org/stable/c/cbadf2575d25e7dcc0d4da2717817ae569fbc99b
- https://git.kernel.org/stable/c/cbc7ec97601d09b74e05e44470fa6b0bcdabf3f5
- https://git.kernel.org/stable/c/fd137bf8149bc6460f9b7b1fc292025da04cb9ee
- https://git.kernel.org/stable/c/8c1882dfee8f404d118020664b73eb4592172226
- https://git.kernel.org/stable/c/9b110a9dcecc59516c77cb3c0caf1f492f75df2d
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.