{"id":"CVE-2025-21737","url":"https://www.cyber-defence.io/tools/cve/CVE-2025-21737","generatedAt":"2026-10-28T03:28:43.489Z","title":"In the Linux kernel, the following vulnerability has been resolved: ceph: fix memory leak in ceph_mds_auth_match() We now free the temporary target path substring allocation on every possible branch, instead of omitting the default branch.","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 [] __kmalloc_noprof+0x359/0x510\n [] ceph_mds_check_access+0x5bf/0x14e0 [ceph]\n [] ceph_open+0x312/0xd80 [ceph]\n [] do_dentry_open+0x456/0x1120\n [] vfs_open+0x79/0x360\n [] path_openat+0x1de5/0x4390\n [] do_filp_open+0x19c/0x3c0\n [] do_sys_openat2+0x141/0x180\n [] __x64_sys_open+0xe5/0x1a0\n [] do_syscall_64+0xb7/0x210\n [] 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=,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 ]","published":"2025-02-27T03:15:14.000Z","lastModified":"2026-06-17T08:44:09.000Z","status":"Modified","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","cvss":{"version":"3.1","score":5.5,"severity":"MEDIUM","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"},"cwe":["CWE-401"],"affected":["linux/linux kernel"],"epss":{"score":0.00208,"percentile":0.10794,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.21%). Track it; it rarely justifies an emergency change on its own."},"changes":[],"references":[{"url":"https://git.kernel.org/stable/c/146109fe936ac07f8f60cd6267543688985b96bc","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/2b6086c5efe5c7bd6e0eb440d96c26ca0d20d9d7","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/3b7d93db450e9d8ead80d75e2a303248f1528c35","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2025-21737","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}