{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2024-36943", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-05-30T15:25:07.073Z", "datePublished": "2024-05-30T15:35:42.119Z", "dateUpdated": "2026-08-05T11:32:11.488Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:32:11.488Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfs/proc/task_mmu: fix loss of young/dirty bits during pagemap scan\n\nmake_uffd_wp_pte() was previously doing:\n\n pte = ptep_get(ptep);\n ptep_modify_prot_start(ptep);\n pte = pte_mkuffd_wp(pte);\n ptep_modify_prot_commit(ptep, pte);\n\nBut if another thread accessed or dirtied the pte between the first 2\ncalls, this could lead to loss of that information. Since\nptep_modify_prot_start() gets and clears atomically, the following is the\ncorrect pattern and prevents any possible race. Any access after the\nfirst call would see an invalid pte and cause a fault:\n\n pte = ptep_modify_prot_start(ptep);\n pte = pte_mkuffd_wp(pte);\n ptep_modify_prot_commit(ptep, pte);" } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H", "baseScore": 7.3, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The vulnerability is reached only through the PAGEMAP_SCAN ioctl on /proc//pagemap combined with a userfaultfd WP-async registration, both of which require local execution on the host. There is no network-facing consumer of this path.\nAC:L - The attacker owns both sides of the race — sibling threads continuously writing to the mapped range set the hardware A/D bits while another thread loops PAGEMAP_SCAN with PM_SCAN_WP_MATCHING over millions of PTEs per iteration, so a hit is effectively guaranteed and can be retried without limit. No condition depends on external state the attacker cannot influence.\nPR:L - Only an ordinary unprivileged local account is needed: pagemap_open() requires just PTRACE_MODE_READ (trivial for /proc/self), the PAGEMAP_SCAN ioctl has no capability check, and userfaultfd_syscall_allowed() unconditionally permits UFFD_USER_MODE_ONLY so even vm.unprivileged_userfaultfd=0 does not block UFFD_FEATURE_WP_ASYNC registration. All required Kconfig options (PROC_PAGE_MONITOR, PTE_MARKER_UFFD_WP) are default-y in distro kernels.\nUI:N - The attacker drives the ioctl and the racing writes entirely from its own threads with no victim action required; when targeting another mm the victim's pre-existing uffd-wp-async registration is passive state, not an interaction.\nS:U - The lost PTE bits corrupt memory managed by the same kernel that contains the flaw, with no crossing of a hypervisor, IOMMU, or sandbox boundary. This is the standard unchanged-scope case for a kernel memory-management defect.\nC:L - Discarding the dirty bit causes a page's rewritten contents to be dropped and the stale swap-slot contents to be resurrected, so data a process deliberately overwrote or scrubbed (keys, credentials) persists in memory and on the swap device instead of being erased. This is a bounded exposure of previously-written data rather than an arbitrary kernel read primitive.\nI:H - Loss of the dirty bit makes the kernel silently drop modified pages — swap-cached anonymous pages revert to stale contents and MADV_FREE pages are discarded to zeros via the try_to_unmap_one discard path — with no error to the application. The attacker can repeat this across an unbounded number of pages, including in another process's mm it can ptrace-read (e.g. a CRIU- or VMM-managed workload using uffd-wp-async dirty tracking), amounting to total loss of integrity of that memory.\nA:H - Pages silently reverting to stale swap contents or being zeroed out corrupts live program state and reliably renders the affected process — including a targeted uffd-wp-async user such as a checkpoint/restore agent or live-migration VMM and its guest — non-functional or crashed. The condition is repeatable at will by an unprivileged local user." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/proc/task_mmu.c" ], "versions": [ { "version": "52526ca7fdb905a768a93f8faa418e9b988fc34b", "lessThan": "74b3d66f91d9f539f99faad74d796fa9a389a015", "status": "affected", "versionType": "git" }, { "version": "52526ca7fdb905a768a93f8faa418e9b988fc34b", "lessThan": "c70dce4982ce1718bf978a35f8e26160b82081f4", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/proc/task_mmu.c" ], "versions": [ { "version": "6.7", "status": "affected" }, { "version": "0", "lessThan": "6.7", "status": "unaffected", "versionType": "semver" }, { "version": "6.8.10", "lessThanOrEqual": "6.8.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.9", "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": "6.7", "versionEndExcluding": "6.8.10" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.9" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/74b3d66f91d9f539f99faad74d796fa9a389a015" }, { "url": "https://git.kernel.org/stable/c/c70dce4982ce1718bf978a35f8e26160b82081f4" } ], "title": "fs/proc/task_mmu: fix loss of young/dirty bits during pagemap scan", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "timestamp": "2024-06-05T18:15:10.001170Z", "id": "CVE-2024-36943", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "role": "CISA Coordinator", "version": "2.0.3" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2024-06-05T18:17:48.241Z" } }, { "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2024-08-02T03:43:50.375Z" }, "title": "CVE Program Container", "references": [ { "url": "https://git.kernel.org/stable/c/74b3d66f91d9f539f99faad74d796fa9a389a015", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/c70dce4982ce1718bf978a35f8e26160b82081f4", "tags": [ "x_transferred" ] } ] } ] } }