{"cve":"CVE-2025-21737","nvd":{"published":"2025-02-27T03:15:14.327","modified":"2026-06-17T08:44:09.493","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nceph: fix memory leak in ceph_mds_auth_match()\n\nWe now free the temporary target path substring allocation on every\npossible branch, instead of omitting the default branch.  In some\ncases, a memory leak occured, which could rapidly crash the system\n(depending on how many file accesses were attempted).\n\nThis was detected in production because it caused a continuous memory\ngrowth, eventually triggering kernel OOM and completely hard-locking\nthe kernel.\n\nRelevant kmemleak stacktrace:\n\n    unreferenced object 0xffff888131e69900 (size 128):\n      comm \"git\", pid 66104, jiffies 4295435999\n      hex dump (first 32 bytes):\n        76 6f 6c 75 6d 65 73 2f 63 6f 6e 74 61 69 6e 65  volumes/containe\n        72 73 2f 67 69 74 65 61 2f 67 69 74 65 61 2f 67  rs/gitea/gitea/g\n      backtrace (crc 2f3bb450):\n        [<ffffffffaa68fb49>] __kmalloc_noprof+0x359/0x510\n        [<ffffffffc32bf1df>] ceph_mds_check_access+0x5bf/0x14e0 [ceph]\n        [<ffffffffc3235722>] ceph_open+0x312/0xd80 [ceph]\n        [<ffffffffaa7dd786>] do_dentry_open+0x456/0x1120\n        [<ffffffffaa7e3729>] vfs_open+0x79/0x360\n        [<ffffffffaa832875>] path_openat+0x1de5/0x4390\n        [<ffffffffaa834fcc>] do_filp_open+0x19c/0x3c0\n        [<ffffffffaa7e44a1>] do_sys_openat2+0x141/0x180\n        [<ffffffffaa7e4945>] __x64_sys_open+0xe5/0x1a0\n        [<ffffffffac2cc2f7>] do_syscall_64+0xb7/0x210\n        [<ffffffffac400130>] entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nIt can be triggered by mouting a subdirectory of a CephFS filesystem,\nand then trying to access files on this subdirectory with an auth token\nusing a path-scoped capability:\n\n    $ ceph auth get client.services\n    [client.services]\n            key = REDACTED\n            caps mds = \"allow rw fsname=cephfs path=/volumes/\"\n            caps mon = \"allow r fsname=cephfs\"\n            caps osd = \"allow rw tag cephfs data=cephfs\"\n\n    $ cat /proc/self/mounts\n    services@[REDACTED].cephfs=/volumes/containers /ceph/containers ceph rw,noatime,name=services,secret=<hidden>,ms_mode=prefer-crc,mount_timeout=300,acl,mon_addr=[REDACTED]:3300,recover_session=clean 0 0\n\n    $ seq 1 1000000 | xargs -P32 --replace={} touch /ceph/containers/file-{} && \\\n    seq 1 1000000 | xargs -P32 --replace={} cat /ceph/containers/file-{}\n\n[ idryomov: combine if statements, rename rc to path_matched and make\n            it a bool, formatting ]","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-401"],"references":["https://git.kernel.org/stable/c/146109fe936ac07f8f60cd6267543688985b96bc","https://git.kernel.org/stable/c/2b6086c5efe5c7bd6e0eb440d96c26ca0d20d9d7","https://git.kernel.org/stable/c/3b7d93db450e9d8ead80d75e2a303248f1528c35"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:59:48.811064707+00:00"},"epss":{"cve":"CVE-2025-21737","score":0.00208,"percentile":0.10917,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}