{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-21919", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-12-29T08:45:45.787Z", "datePublished": "2025-04-01T15:40:54.075Z", "dateUpdated": "2026-08-05T11:55:20.805Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:55:20.805Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsched/fair: Fix potential memory corruption in child_cfs_rq_on_list\n\nchild_cfs_rq_on_list attempts to convert a 'prev' pointer to a cfs_rq.\nThis 'prev' pointer can originate from struct rq's leaf_cfs_rq_list,\nmaking the conversion invalid and potentially leading to memory\ncorruption. Depending on the relative positions of leaf_cfs_rq_list and\nthe task group (tg) pointer within the struct, this can cause a memory\nfault or access garbage data.\n\nThe issue arises in list_add_leaf_cfs_rq, where both\ncfs_rq->leaf_cfs_rq_list and rq->leaf_cfs_rq_list are added to the same\nleaf list. Also, rq->tmp_alone_branch can be set to rq->leaf_cfs_rq_list.\n\nThis adds a check `if (prev == &rq->leaf_cfs_rq_list)` after the main\nconditional in child_cfs_rq_on_list. This ensures that the container_of\noperation will convert a correct cfs_rq struct.\n\nThis check is sufficient because only cfs_rqs on the same CPU are added\nto the list, so verifying the 'prev' pointer against the current rq's list\nhead is enough.\n\nFixes a potential memory corruption issue that due to current struct\nlayout might not be manifesting as a crash but could lead to unpredictable\nbehavior when the layout changes." } ], "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 defect is in core CFS scheduler code (`kernel/sched/fair.c`) reached through ordinary local scheduling activity, cgroup manipulation, and CFS-bandwidth unthrottling; there is no network-facing input path. Exploitation requires the ability to run code on the machine.\nAC:L - The invalid `container_of()` executes deterministically every time the examined cfs_rq is first on `rq->leaf_cfs_rq_list` or `rq->tmp_alone_branch` is at its reset value, which is the normal steady state — no race to win and no unusual precondition. An attacker reliably drives it by creating/loading a cgroup in a delegated subtree and letting the load balancer or bandwidth timer run.\nPR:L - No capability check, credential test, or privileged gate exists on `__update_blocked_fair()` or `tg_unthrottle_up()`; an ordinary unprivileged user reaches both via normal task execution and via cgroup v2 cpu/cpu.max controls in a systemd- or container-delegated subtree. Real root in the init namespace is not needed.\nUI:N - The vulnerable path runs from the periodic load-balance softirq and the CFS bandwidth timer, with no victim action of any kind required. The attacker's own workload is sufficient to trigger it.\nS:U - The bogus pointer arithmetic, out-of-bounds read, and any resulting fault all occur within the kernel's own security authority on the same host. No VM, IOMMU, or sandbox boundary is crossed.\nC:H - The type-confused `struct task_group *` is dereferenced at `offsetof(task_group, parent)` from a `list_head` address, which reads out of bounds past the end of the `cfs_rq` slab object into adjacent heap memory whose contents an attacker can influence via heap grooming. This is an unbounded kernel-memory read at an offset determined by struct layout rather than by any bounds check.\nI:H - This is a genuine type confusion — a `struct rq` list head reinterpreted as a member of `struct cfs_rq`, yielding a fabricated object pointer that is dereferenced — which upstream explicitly characterizes as \"potential memory corruption.\" Under differing struct layouts the fabricated `tg` pointer is an arbitrary non-pointer value, so the corrupted access is not confined to a benign read.\nA:H - The commit states the invalid conversion \"can cause a memory fault or access garbage data\"; dereferencing a wild `tg` pointer inside the scheduler with the rq lock held produces an oops or panic, and the slab-out-of-bounds read triggers a KASAN report that panics on hardened configurations. A fault in `__update_blocked_fair()` under the runqueue lock is unrecoverable for the affected CPU." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "kernel/sched/fair.c" ], "versions": [ { "version": "fdaba61ef8a268d4136d0a113d153f7a89eb9984", "lessThan": "5cb300dcdd27e6a351ac02541e0231261c775852", "status": "affected", "versionType": "git" }, { "version": "fdaba61ef8a268d4136d0a113d153f7a89eb9984", "lessThan": "000c9ee43928f2ce68a156dd40bab7616256f4dd", "status": "affected", "versionType": "git" }, { "version": "fdaba61ef8a268d4136d0a113d153f7a89eb9984", "lessThan": "9cc7f0018609f75a349e42e3aebc3b0e905ba775", "status": "affected", "versionType": "git" }, { "version": "fdaba61ef8a268d4136d0a113d153f7a89eb9984", "lessThan": "b5741e4b9ef3567613b2351384f91d3f16e59986", "status": "affected", "versionType": "git" }, { "version": "fdaba61ef8a268d4136d0a113d153f7a89eb9984", "lessThan": "e1dd09df30ba86716cb2ffab97dc35195c01eb8f", "status": "affected", "versionType": "git" }, { "version": "fdaba61ef8a268d4136d0a113d153f7a89eb9984", "lessThan": "3b4035ddbfc8e4521f85569998a7569668cccf51", "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/sched/fair.c" ], "versions": [ { "version": "5.13", "status": "affected" }, { "version": "0", "lessThan": "5.13", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.179", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.131", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.83", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.19", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.13.7", "lessThanOrEqual": "6.13.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.14", "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": "5.13", "versionEndExcluding": "5.15.179" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "6.1.131" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "6.6.83" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "6.12.19" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "6.13.7" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "6.14" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/5cb300dcdd27e6a351ac02541e0231261c775852" }, { "url": "https://git.kernel.org/stable/c/000c9ee43928f2ce68a156dd40bab7616256f4dd" }, { "url": "https://git.kernel.org/stable/c/9cc7f0018609f75a349e42e3aebc3b0e905ba775" }, { "url": "https://git.kernel.org/stable/c/b5741e4b9ef3567613b2351384f91d3f16e59986" }, { "url": "https://git.kernel.org/stable/c/e1dd09df30ba86716cb2ffab97dc35195c01eb8f" }, { "url": "https://git.kernel.org/stable/c/3b4035ddbfc8e4521f85569998a7569668cccf51" } ], "title": "sched/fair: Fix potential memory corruption in child_cfs_rq_on_list", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "cvssV3_1": { "scope": "UNCHANGED", "version": "3.1", "baseScore": 7.8, "attackVector": "LOCAL", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "HIGH" } }, { "other": { "type": "ssvc", "content": { "id": "CVE-2025-21919", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "total" } ], "version": "2.0.3", "timestamp": "2025-10-01T19:23:59.713530Z" } } } ], "problemTypes": [ { "descriptions": [ { "lang": "en", "type": "CWE", "cweId": "CWE-787", "description": "CWE-787 Out-of-bounds Write" } ] } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2025-10-01T19:26:33.844Z" } }, { "title": "CVE Program Container", "references": [ { "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T19:39:11.086Z" } }, { "x_adpType": "supplier", "providerMetadata": { "orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e", "shortName": "siemens-SADP", "dateUpdated": "2026-07-14T12:40:29.493Z" }, "affected": [ { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" } ], "references": [ { "url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html" } ] } ] } }