{"id":"CVE-2026-72213","state":"PUBLISHED","title":"mm/hugetlb: fix hugetlb cgroup rsvd charge/uncharge mismatch","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/hugetlb: fix hugetlb cgroup rsvd charge/uncharge mismatch\n\nIn alloc_hugetlb_folio(), a single h_cg pointer is used for both the rsvd\nand non-rsvd hugetlb cgroup charges.  When map_chg is set,\nhugetlb_cgroup_charge_cgroup_rsvd() stores the charged cgroup in h_cg, but\nthe immediately following hugetlb_cgroup_charge_cgroup() overwrites h_cg\nwith the non-rsvd cgroup pointer.\n\nAs a result, hugetlb_cgroup_commit_charge_rsvd() stores the wrong\n(non-rsvd) cgroup pointer into the folio's rsvd slot.\n\nWhen the folio is later freed, free_huge_folio() unconditionally calls\nboth hugetlb_cgroup_uncharge_folio() and\nhugetlb_cgroup_uncharge_folio_rsvd().  The rsvd uncharge reads back the\nwrong cgroup from the folio and decrements a counter that was never\ncharged for that cgroup, causing a page_counter underflow:\n\n  page_counter underflow: -512 nr_pages=512\n  WARNING: mm/page_counter.c:61 at page_counter_cancel\n\nFix this by introducing a separate h_cg_rsvd pointer exclusively for the\nrsvd charge path, keeping the rsvd and non-rsvd charges fully independent\nthrough their charge, commit, and error uncharge paths.","publishedAt":"2026-08-15T05:54:07.854Z","updatedAt":"2026-10-30T12:28:57.670Z","severity":{"score":7.1,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"08cf9faf7558020aed6a0da5810b824b07139dfa","status":"affected","lessThan":"f8dfdf725bccb0ae41eead2f6da8183727218855","versionType":"git"},{"version":"08cf9faf7558020aed6a0da5810b824b07139dfa","status":"affected","lessThan":"043c509f2488033c68c46d2de2af082fcd568612","versionType":"git"},{"version":"08cf9faf7558020aed6a0da5810b824b07139dfa","status":"affected","lessThan":"5c32ae4a91fb5f4941328e0c1720a7fa4189c3bd","versionType":"git"},{"version":"08cf9faf7558020aed6a0da5810b824b07139dfa","status":"affected","lessThan":"1697d253f51cf5e3825a3423ff49e128a3502ab2","versionType":"git"},{"version":"08cf9faf7558020aed6a0da5810b824b07139dfa","status":"affected","lessThan":"b785f2bd9496facedc0a031be09cddcd1d3c84d3","versionType":"git"},{"version":"08cf9faf7558020aed6a0da5810b824b07139dfa","status":"affected","lessThan":"15807d0ddde37407af72859426b654f3d1972b00","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/hugetlb.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.7","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.7","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.101","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/hugetlb.c"]}],"references":["https://git.kernel.org/stable/c/f8dfdf725bccb0ae41eead2f6da8183727218855","https://git.kernel.org/stable/c/043c509f2488033c68c46d2de2af082fcd568612","https://git.kernel.org/stable/c/5c32ae4a91fb5f4941328e0c1720a7fa4189c3bd","https://git.kernel.org/stable/c/1697d253f51cf5e3825a3423ff49e128a3502ab2","https://git.kernel.org/stable/c/b785f2bd9496facedc0a031be09cddcd1d3c84d3","https://git.kernel.org/stable/c/15807d0ddde37407af72859426b654f3d1972b00"],"weaknesses":[],"ingestedAt":"2026-10-30T12:48:04.825Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/72xxx/CVE-2026-72213.json","commit":"1f312381e38164a43607eebab851b151dd16861e","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-72213","state":"PUBLISHED","datePublished":"2026-08-15T05:54:07.854Z","dateUpdated":"2026-10-30T12:28:57.670Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-09T03:40:39.912Z"},"containers":{"cna":{"title":"mm/hugetlb: fix hugetlb cgroup rsvd charge/uncharge mismatch","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/hugetlb: fix hugetlb cgroup rsvd charge/uncharge mismatch\n\nIn alloc_hugetlb_folio(), a single h_cg pointer is used for both the rsvd\nand non-rsvd hugetlb cgroup charges.  When map_chg is set,\nhugetlb_cgroup_charge_cgroup_rsvd() stores the charged cgroup in h_cg, but\nthe immediately following hugetlb_cgroup_charge_cgroup() overwrites h_cg\nwith the non-rsvd cgroup pointer.\n\nAs a result, hugetlb_cgroup_commit_charge_rsvd() stores the wrong\n(non-rsvd) cgroup pointer into the folio's rsvd slot.\n\nWhen the folio is later freed, free_huge_folio() unconditionally calls\nboth hugetlb_cgroup_uncharge_folio() and\nhugetlb_cgroup_uncharge_folio_rsvd().  The rsvd uncharge reads back the\nwrong cgroup from the folio and decrements a counter that was never\ncharged for that cgroup, causing a page_counter underflow:\n\n  page_counter underflow: -512 nr_pages=512\n  WARNING: mm/page_counter.c:61 at page_counter_cancel\n\nFix this by introducing a separate h_cg_rsvd pointer exclusively for the\nrsvd charge path, keeping the rsvd and non-rsvd charges fully independent\nthrough their charge, commit, and error uncharge paths."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"08cf9faf7558020aed6a0da5810b824b07139dfa","status":"affected","lessThan":"f8dfdf725bccb0ae41eead2f6da8183727218855","versionType":"git"},{"version":"08cf9faf7558020aed6a0da5810b824b07139dfa","status":"affected","lessThan":"043c509f2488033c68c46d2de2af082fcd568612","versionType":"git"},{"version":"08cf9faf7558020aed6a0da5810b824b07139dfa","status":"affected","lessThan":"5c32ae4a91fb5f4941328e0c1720a7fa4189c3bd","versionType":"git"},{"version":"08cf9faf7558020aed6a0da5810b824b07139dfa","status":"affected","lessThan":"1697d253f51cf5e3825a3423ff49e128a3502ab2","versionType":"git"},{"version":"08cf9faf7558020aed6a0da5810b824b07139dfa","status":"affected","lessThan":"b785f2bd9496facedc0a031be09cddcd1d3c84d3","versionType":"git"},{"version":"08cf9faf7558020aed6a0da5810b824b07139dfa","status":"affected","lessThan":"15807d0ddde37407af72859426b654f3d1972b00","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/hugetlb.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.7","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.7","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.101","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/hugetlb.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/f8dfdf725bccb0ae41eead2f6da8183727218855"},{"url":"https://git.kernel.org/stable/c/043c509f2488033c68c46d2de2af082fcd568612"},{"url":"https://git.kernel.org/stable/c/5c32ae4a91fb5f4941328e0c1720a7fa4189c3bd"},{"url":"https://git.kernel.org/stable/c/1697d253f51cf5e3825a3423ff49e128a3502ab2"},{"url":"https://git.kernel.org/stable/c/b785f2bd9496facedc0a031be09cddcd1d3c84d3"},{"url":"https://git.kernel.org/stable/c/15807d0ddde37407af72859426b654f3d1972b00"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H","baseScore":7.1,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The bug is in alloc_hugetlb_folio()/free_huge_folio() and is reached only via local MM paths (mmap/munmap, hugetlb page faults, fallocate, memfd MFD_HUGETLB, MAP_HUGETLB) that syzbot triggered through hugetlbfs inode eviction, not via any network-facing kernel service.\nAC:L - An unprivileged attacker can reliably trigger the mismatch by creating hugetlbfs mappings without reservations (MAP_NORESERVE or fault-before-reserve), faulting in huge pages to run alloc_hugetlb_folio() with map_chg set, then closing/unmapping to free folios and hit the bad rsvd uncharge.\nPR:L - Triggering requires only an unprivileged local process that can use hugetlb memory (hugetlbfs/MAP_HUGETLB/memfd) under a hugetlb cgroup; no init-namespace root or special driver capabilities are needed, and cgroup hugetlb limits are controllable from user namespaces.\nUI:N - Exploitation is fully attacker-driven through normal syscalls (mmap, write/fault, close/unlink) and does not require any victim user action beyond the attacker operating on their own mappings.\nS:U - Impact is confined to kernel hugetlb/cgroup page_counter accounting within the same host kernel security domain; it does not cross VM, container runtime, or IOMMU boundaries.\nC:N - The flaw corrupts hugetlb cgroup reservation counters and emits a WARN on underflow; it does not read or disclose kernel memory, pointers, or other confidential data to the attacker.\nI:H - page_counter underflow forcibly resets hugetlb cgroup reservation usage to zero, corrupting kernel accounting so an attacker can bypass hugetlb.rsvd cgroup limits and consume hugepage resources beyond enforced quotas in multi-tenant/container deployments.\nA:H - free_huge_folio() unconditionally hits the bad rsvd uncharge and triggers a kernel WARNING/page_counter underflow during hugepage teardown; syzbot classified this as DoS and repeated alloc/free cycles can disrupt hugetlb availability for other workloads when limits are bypassed."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:28:57.670Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"6.12.101"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"6.18.40"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"7.1.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-72213","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-10-16T18:43:53.609919Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-16T18:45:01.945Z"}}]}}}