{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-43376", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-05-01T14:12:56.006Z", "datePublished": "2026-05-08T14:21:25.854Z", "dateUpdated": "2026-08-05T12:27:35.730Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:27:35.730Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix use-after-free by using call_rcu() for oplock_info\n\nksmbd currently frees oplock_info immediately using kfree(), even\nthough it is accessed under RCU read-side critical sections in places\nlike opinfo_get() and proc_show_files().\n\nSince there is no RCU grace period delay between nullifying the pointer\nand freeing the memory, a reader can still access oplock_info\nstructure after it has been freed. This can leads to a use-after-free\nespecially in opinfo_get() where atomic_inc_not_zero() is called on\nalready freed memory.\n\nFix this by switching to deferred freeing using call_rcu()." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - ksmbd is the in-kernel SMB server reachable over TCP/445, and the vulnerable oplock_info lifetime is exercised by remote SMB2 create/close/oplock and lease operations.\nAC:L - The attacker can create oplocks/leases and drive concurrent requests over SMB connections, so the race is attacker-controlled rather than dependent on an external victim condition.\nPR:N - The path is post-session/tree-connect, but ksmbd supports guest/public shares; in the highest reasonable oplocks-enabled guest-share deployment, no prior credentials are needed.\nUI:N - No victim user action is required once the SMB service and share are available; the attacker sends network protocol requests directly.\nS:U - The vulnerable component and impacted resources are the same kernel/host security authority, with no VM, hypervisor, or other scope boundary crossing.\nC:H - This is a kernel heap use-after-free on oplock_info, including stale pointer dereferences after freed memory can be reallocated, which can reasonably enable high-impact kernel information disclosure.\nI:H - The stale atomic_inc_not_zero and later field accesses can corrupt a reallocated kernel object, making arbitrary kernel memory modification or code execution defensible.\nA:H - The UAF can directly trigger kernel memory corruption, oops, panic, or hang, causing high availability impact." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/server/oplock.c", "fs/smb/server/oplock.h" ], "versions": [ { "version": "296cb5457cc6f4a754c4ae29855f8a253d52bcc6", "lessThan": "302fef75512b2c8329a3f5efab1ae7ba2562387a", "status": "affected", "versionType": "git" }, { "version": "d54ab1520d43e95f9b2e22d7a05fc9614192e5a5", "lessThan": "08aa9f3c8cf4d0bee44df540dfe34e8d64069f2c", "status": "affected", "versionType": "git" }, { "version": "18b4fac5ef17f77fed9417d22210ceafd6525fc7", "lessThan": "1d6abf145615dbfe267ce3b0a271f95e3780e18e", "status": "affected", "versionType": "git" }, { "version": "18b4fac5ef17f77fed9417d22210ceafd6525fc7", "lessThan": "ce8507ee82c888126d8e7565e27c016308d24cde", "status": "affected", "versionType": "git" }, { "version": "18b4fac5ef17f77fed9417d22210ceafd6525fc7", "lessThan": "1dfd062caa165ec9d7ee0823087930f3ab8a6294", "status": "affected", "versionType": "git" }, { "version": "d73686367ad68534257cd88a36ca3c52cb8b81d8", "status": "affected", "versionType": "git" }, { "version": "6.6.88", "lessThan": "6.6.130", "status": "affected", "versionType": "semver" }, { "version": "6.12.25", "lessThan": "6.12.78", "status": "affected", "versionType": "semver" }, { "version": "6.14.4", "lessThan": "6.15", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/server/oplock.c", "fs/smb/server/oplock.h" ], "versions": [ { "version": "6.15", "status": "affected" }, { "version": "0", "lessThan": "6.15", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.130", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.78", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.19", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.19.9", "lessThanOrEqual": "6.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0", "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": "6.6.88", "versionEndExcluding": "6.6.130" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12.25", "versionEndExcluding": "6.12.78" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.15", "versionEndExcluding": "6.18.19" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.15", "versionEndExcluding": "6.19.9" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.15", "versionEndExcluding": "7.0" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.14.4" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/302fef75512b2c8329a3f5efab1ae7ba2562387a" }, { "url": "https://git.kernel.org/stable/c/08aa9f3c8cf4d0bee44df540dfe34e8d64069f2c" }, { "url": "https://git.kernel.org/stable/c/1d6abf145615dbfe267ce3b0a271f95e3780e18e" }, { "url": "https://git.kernel.org/stable/c/ce8507ee82c888126d8e7565e27c016308d24cde" }, { "url": "https://git.kernel.org/stable/c/1dfd062caa165ec9d7ee0823087930f3ab8a6294" } ], "title": "ksmbd: fix use-after-free by using call_rcu() for oplock_info", "x_generator": { "engine": "bippy-1.2.0" } } } }