{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-40201", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T07:20:57.178Z", "datePublished": "2025-11-12T21:56:34.063Z", "dateUpdated": "2026-08-05T12:08:29.919Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:08:29.919Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nkernel/sys.c: fix the racy usage of task_lock(tsk->group_leader) in sys_prlimit64() paths\n\nThe usage of task_lock(tsk->group_leader) in sys_prlimit64()->do_prlimit()\npath is very broken.\n\nsys_prlimit64() does get_task_struct(tsk) but this only protects task_struct\nitself. If tsk != current and tsk is not a leader, this process can exit/exec\nand task_lock(tsk->group_leader) may use the already freed task_struct.\n\nAnother problem is that sys_prlimit64() can race with mt-exec which changes\n->group_leader. In this case do_prlimit() may take the wrong lock, or (worse)\n->group_leader may change between task_lock() and task_unlock().\n\nChange sys_prlimit64() to take tasklist_lock when necessary. This is not\nnice, but I don't see a better fix for -stable." } ], "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 vulnerability is reached through the `prlimit64()` syscall (and pid-targeted setrlimit paths) from a local process; no network or physical vector is involved.\nAC:L - The attacker drives both sides of the race using their own processes — one loop calling prlimit64() on a non-leader TID while a co-operating multithreaded process repeatedly performs mt-exec or group-exit-and-reap — and can retry indefinitely until the window is hit.\nPR:L - check_prlimit_permission() grants access on a plain uid/gid match, so any unprivileged local user can target a non-leader thread of a process they own; no CAP_SYS_RESOURCE or root is required, and it works unrestricted inside containers.\nUI:N - The attacker creates the victim threads, the exec/exit, and the racing syscall entirely on their own; no action by any other user is needed.\nS:U - The corruption and its consequences stay within the kernel's own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - Use-after-free on a task_struct: update_rlimit_cpu() dereferences the freed leader's ->sighand/->signal, and an attacker who reallocates the slot via fork() spraying can leverage the dangling-pointer reads for kernel memory disclosure.\nI:H - The UAF gives write primitives — spin_lock/spin_unlock words written into freed memory plus an attacker-supplied RLIMIT_CPU value written through a dangling sighand/signal pointer — sufficient to corrupt a reallocated live task_struct and pursue control-flow hijack.\nA:H - The mismatched task_lock()/task_unlock() across a de_thread() leaves a task's alloc_lock permanently held, deadlocking every subsequent task_lock() user (/proc readers, exec, fs_struct access), and the UAF itself readily oopses/panics the kernel." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "kernel/sys.c" ], "versions": [ { "version": "18c91bb2d87268d23868bf13508f5bc9cf04e89a", "lessThan": "1bc0d9315ef5296abb2c9fd840336255850ded18", "status": "affected", "versionType": "git" }, { "version": "18c91bb2d87268d23868bf13508f5bc9cf04e89a", "lessThan": "132f827e7bac7373e1522e89709d70b43cae5342", "status": "affected", "versionType": "git" }, { "version": "18c91bb2d87268d23868bf13508f5bc9cf04e89a", "lessThan": "19b45c84bd9fd42fa97ff80c6350d604cb871c75", "status": "affected", "versionType": "git" }, { "version": "18c91bb2d87268d23868bf13508f5bc9cf04e89a", "lessThan": "6796412decd2d8de8ec708213bbc958fab72f143", "status": "affected", "versionType": "git" }, { "version": "18c91bb2d87268d23868bf13508f5bc9cf04e89a", "lessThan": "a15f37a40145c986cdf289a4b88390f35efdecc4", "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/sys.c" ], "versions": [ { "version": "5.18", "status": "affected" }, { "version": "0", "lessThan": "5.18", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.157", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.113", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.54", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.17.4", "lessThanOrEqual": "6.17.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18", "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": "5.18", "versionEndExcluding": "6.1.157" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "6.6.113" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "6.12.54" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "6.17.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18", "versionEndExcluding": "6.18" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/1bc0d9315ef5296abb2c9fd840336255850ded18" }, { "url": "https://git.kernel.org/stable/c/132f827e7bac7373e1522e89709d70b43cae5342" }, { "url": "https://git.kernel.org/stable/c/19b45c84bd9fd42fa97ff80c6350d604cb871c75" }, { "url": "https://git.kernel.org/stable/c/6796412decd2d8de8ec708213bbc958fab72f143" }, { "url": "https://git.kernel.org/stable/c/a15f37a40145c986cdf289a4b88390f35efdecc4" } ], "title": "kernel/sys.c: fix the racy usage of task_lock(tsk->group_leader) in sys_prlimit64() paths", "x_generator": { "engine": "bippy-1.2.0" } } } }