{"cve":"CVE-2025-38527","nvd":{"published":"2025-08-16T12:15:28.183","modified":"2026-10-15T22:18:44.583","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix use-after-free in cifs_oplock_break\n\nA race condition can occur in cifs_oplock_break() leading to a\nuse-after-free of the cinode structure when unmounting:\n\n  cifs_oplock_break()\n    _cifsFileInfo_put(cfile)\n      cifsFileInfo_put_final()\n        cifs_sb_deactive()\n          [last ref, start releasing sb]\n            kill_sb()\n              kill_anon_super()\n                generic_shutdown_super()\n                  evict_inodes()\n                    dispose_list()\n                      evict()\n                        destroy_inode()\n                          call_rcu(&inode->i_rcu, i_callback)\n    spin_lock(&cinode->open_file_lock)  <- OK\n                            [later] i_callback()\n                              cifs_free_inode()\n                                kmem_cache_free(cinode)\n    spin_unlock(&cinode->open_file_lock)  <- UAF\n    cifs_done_oplock_break(cinode)       <- UAF\n\nThe issue occurs when umount has already released its reference to the\nsuperblock. When _cifsFileInfo_put() calls cifs_sb_deactive(), this\nreleases the last reference, triggering the immediate cleanup of all\ninodes under RCU. However, cifs_oplock_break() continues to access the\ncinode after this point, resulting in use-after-free.\n\nFix this by holding an extra reference to the superblock during the\nentire oplock break operation. This ensures that the superblock and\nits inodes remain valid until the oplock break completes.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8},"cwes":["CWE-416"],"references":["https://git.kernel.org/stable/c/09bce2138a30ef10d8821c8c3f73a4ab7a5726bc","https://git.kernel.org/stable/c/0a4eec84d4d2c4085d4ed8630fd74e4b39033c1b","https://git.kernel.org/stable/c/2baaf5bbab2ac474c4f92c10fcb3310f824db995","https://git.kernel.org/stable/c/4256a483fe58af66a46cbf3dc48ff26e580d3308","https://git.kernel.org/stable/c/705c79101ccf9edea5a00d761491a03ced314210"],"products":["debian:debian_linux","linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:06:45.861874017+00:00"},"epss":{"cve":"CVE-2025-38527","score":0.00431,"percentile":0.37121,"date":"2026-10-25"},"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."]}