{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-89500", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.715Z", "datePublished": "2026-09-11T19:43:49.392Z", "dateUpdated": "2026-10-19T08:47:51.845Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:47:51.845Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nring-buffer: Make cpu_buffer::free_page a buffer_data_read_page\n\nDiscarding a cached reader page after a concurrent ring buffer resize\nuses the new global subbuf_order for the free_pages() call. This\nmismatched order may crashes the kernel or leaks memory because the cached\npage was allocated under the old size.\n\nSave the actual free_page order alongside the page address to ensure we\nalways refer to the correct value and do not rely on the potentially\nstalled cpu_buffer->subbuf_order value. The simplest is to make\nfree_page a buffer_data_read_page which already covers exactly what we\nneed: a page address and a page order." } ], "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 reached only via local tracefs: write() to buffer_subbuf_size_kb (buffer_subbuf_size_write -> ring_buffer_subbuf_order_set) racing read/splice/close of per_cpu/cpuN/trace_pipe_raw (ring_buffer_alloc_read_page / ring_buffer_free_read_page) or instance rmdir (rb_free_cpu_buffer). No network, adjacent-radio, or physical path exists.\nAC:L - The attacker owns both sides of the race: one thread toggles buffer_subbuf_size_kb while another caches or discards a reader page via trace_pipe_raw. The window includes synchronize_rcu() and GFP_KERNEL allocation of every new sub-buffer, so the mismatch is reliably retryable with no condition outside attacker control.\nPR:L - tracing_check_open_get_tr() enforces only LOCKDOWN_TRACEFS and DAC, with no capable() check. buffer_subbuf_size_kb is 0640 and trace_pipe_raw is 0440; Android/Perfetto, ChromeOS, and distro tracing groups routinely delegate these to unprivileged accounts, matching CVE-2024-50207, CVE-2025-38101, and CVE-2026-74634.\nUI:N - Exploitation uses the attacker's own file descriptors and threads (write buffer_subbuf_size_kb, read/close trace_pipe_raw, optional instance rmdir). No separate victim mount, click, or configuration action is required.\nS:U - Wrong-order free_pages() and reuse of a cached reader page corrupt kernel ring-buffer and buddy-allocator pages within the same OS security authority. This enables local privilege escalation but does not cross VM, IOMMU, container, or hardware trust boundaries.\nC:H - cpu_buffer->free_page stored no allocation order, so a cached page allocated under the old subbuf size can be discarded or reused with the new order. Over-free and undersized-page swap are page UAF/OOB reads; recycled buddy pages and ring-buffer contents can be disclosed through subsequent trace_pipe_raw reads.\nI:H - free_pages() with a larger-than-allocated order returns neighboring in-use pages to the buddy allocator (page UAF/write). ring_buffer_read_page() can also swap that undersized cached page into the live writer path, producing out-of-bounds kernel stores exploitable for control-flow hijack.\nA:H - Mismatched-order free_pages() corrupts the buddy allocator and the commit states this may crash the kernel; UAF/OOB on ring-buffer pages also oops/panic. The attacker chooses the order delta via buffer_subbuf_size_kb and can retrigger the race at will." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "kernel/trace/ring_buffer.c" ], "versions": [ { "version": "8e7b58c27b3c567316a51079b375b846f9223bba", "lessThan": "d8f52dc3c3f1f987d8cf920ccd8d66590870bf3f", "status": "affected", "versionType": "git" }, { "version": "8e7b58c27b3c567316a51079b375b846f9223bba", "lessThan": "a1dabe68fb53730bc0be60c5dbfd3f4c560084e7", "status": "affected", "versionType": "git" }, { "version": "8e7b58c27b3c567316a51079b375b846f9223bba", "lessThan": "d787d509bdf6c88c85e095247daf7456cb7fb772", "status": "affected", "versionType": "git" }, { "version": "8e7b58c27b3c567316a51079b375b846f9223bba", "lessThan": "7a1fb95de5404134f8758c1295ce88986bdf117c", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "kernel/trace/ring_buffer.c" ], "versions": [ { "version": "6.8", "status": "affected" }, { "version": "0", "lessThan": "6.8", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.112", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.51", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "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": "6.8", "versionEndExcluding": "6.12.112" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "6.18.51" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "7.2.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/d8f52dc3c3f1f987d8cf920ccd8d66590870bf3f" }, { "url": "https://git.kernel.org/stable/c/a1dabe68fb53730bc0be60c5dbfd3f4c560084e7" }, { "url": "https://git.kernel.org/stable/c/d787d509bdf6c88c85e095247daf7456cb7fb772" }, { "url": "https://git.kernel.org/stable/c/7a1fb95de5404134f8758c1295ce88986bdf117c" } ], "title": "ring-buffer: Make cpu_buffer::free_page a buffer_data_read_page", "x_generator": { "engine": "bippy-1.2.0" } } } }