CVE-2026-45955

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Any remote party must already cause writes through local VFS/block access (e.g., a file on an md-backed volume).\nAC:L - On a system with llbitmap enabled, an attacker can reliably force the timeout by racing the periodic daemon against many concurrent writes to the same bitmap page that hold `percpu_ref` until `daemon_sleep` expires; both sides of the race are attacker-driven I/O patterns.\nPR:L - Exploitation does not require real root in the init namespace: any principal that can issue writes to storage backed by an affected md array (typical unprivileged user on a multi-tenant NAS, or a member of the `disk` group with raw `/dev/md*` access) reaches the vulnerable code.\nUI:N - Triggering the race requires only sustained automated write I/O; no victim click, mount dialog, or other interactive action is needed beyond normal storage use.\nS:U - Impact stays within kernel/MD RAID scope (hang and bitmap inconsistency on the host); it does not cross a VM, container, or IOMMU security boundary.\nC:N - This is a refcount lifecycle logic bug, not memory corruption; there is no out-of-bounds access, UAF, or other primitive that discloses kernel memory.\nI:H - After the bug, `llbitmap_raise_barrier()` can block new writes before `llbitmap_state_machine()` runs, so dirty regions may not be recorded; combined with uncleared dirty bits on other paths, RAID resync decisions can be wrong after crash\u2014high integrity risk for redundant storage.\nA:H - A permanently killed `percpu_ref` leaves writers stuck in uninterruptible `wait_event` in `llbitmap_raise_barrier()`, causing indefinite write hangs (effective DoS) for affected bitmap pages on production NAS/RAID systems."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/md/md-llbitmap.c"], "versions": [{"version": "5ab829f1971dc99f2aac10846c378e67fc875abc", "lessThan": "095417d6b669c2dec39a5842ccb94df915f97f54", "status": "affected", "versionType": "git"}, {"version": "5ab829f1971dc99f2aac10846c378e67fc875abc", "lessThan": "2446d099350185caeed19ab2c0270451a97296fb", "status": "affected", "versionType": "git"}, {"version": "5ab829f1971dc99f2aac10846c378e67fc875abc", "lessThan": "d119bd2e1643cc023210ff3c6f0657e4f914e71d", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/md/md-llbitmap.c"], "versions": [{"version": "6.18", "status": "affected"}, {"version": "0", "lessThan": "6.18", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.14", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.19.4", "lessThanOrEqual": "6.19.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.0", "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": "6.18", "versionEndExcluding": "6.18.14"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.18", "versionEndExcluding": "6.19.4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.18", "versionEndExcluding": "7.0"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/095417d6b669c2dec39a5842ccb94df915f97f54"}, {"url": "https://git.kernel.org/stable/c/2446d099350185caeed19ab2c0270451a97296fb"}, {"url": "https://git.kernel.org/stable/c/d119bd2e1643cc023210ff3c6f0657e4f914e71d"}], "title": "md/md-llbitmap: fix percpu_ref not resurrected on suspend timeout", "x_generator": {"engine": "bippy-1.2.0"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-45955", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-10-16T15:18:35.481520Z"}}}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-404", "description": "CWE-404 Improper Resource Shutdown or Release"}]}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-19T19:26:40.445Z"}}]}}

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{"bugzilla": {"description": "kernel: md/md-llbitmap: fix percpu_ref not resurrected on suspend timeout", "id": "2481998", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2481998"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-911", "details": ["A flaw was found in the Linux kernel's `md/md-llbitmap` component. This vulnerability occurs when a suspend operation times out, failing to properly reset a critical internal reference. This oversight leaves the system's page control structure in an unusable state. This issue can lead to system instability or a Denial of Service (DoS), where the system becomes unresponsive."], "name": "CVE-2026-45955", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-05-27T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-45955\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-45955\nhttps://lore.kernel.org/linux-cve-announce/2026052732-CVE-2026-45955-00bf@gregkh/T"], "threat_severity": "Low"}

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