{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2024-50086", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-10-21T19:36:19.942Z", "datePublished": "2024-10-29T00:50:29.284Z", "dateUpdated": "2026-08-05T11:41:31.690Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:41:31.690Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix user-after-free from session log off\n\nThere is racy issue between smb2 session log off and smb2 session setup.\nIt will cause user-after-free from session log off.\nThis add session_lock when setting SMB2_SESSION_EXPIRED and referece\ncount to session struct not to free session while it is being used." } ], "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 processing attacker-supplied SMB2 PDUs on TCP/445 (or RDMA), so the entire race is driven by remote network traffic. No local access to the target is required.\nAC:L - The attacker controls both sides of the race — one pipelined SMB2 request holds the raw `work->sess` pointer while a second concurrently issued SMB2_SESSION_SETUP drives `ksmbd_expire_session()` into `kfree(sess)` — and each PDU is dispatched to a separate workqueue item, so the race can be replayed indefinitely and widened with compound/large requests.\nPR:N - No credentials are needed: `__session_create()` leaves a session `SMB2_SESSION_IN_PROGRESS` and `smb2_sess_setup()`'s error path marks it `SMB2_SESSION_EXPIRED`, both of which `ksmbd_expire_session()` frees, while the concurrent work item still dereferences `work->sess` in `smb3_preauth_hash_rsp()`/`set_sign_rsp()` after `ksmbd_conn_unlock()`. The logoff variant needs only an ordinary (including guest-mapped) SMB session.\nUI:N - The attacker triggers everything by sending SMB2 requests to the listening ksmbd server; no action by any local user or administrator is involved.\nS:U - The corruption and its consequences stay within the kernel's own security authority on the SMB server host, with no crossing of a VM, sandbox, or IOMMU boundary.\nC:H - After the free, `set_sign_rsp()` HMACs the response with `sess->smb3signingkey` read from reclaimed slab memory and returns the result to the attacker, and `sess->file_table`/`sess->tree_conns` lookups on freed xarrays yield attacker-influenced pointers, enabling disclosure of arbitrary kernel memory.\nI:H - `smb3_preauth_hash_rsp()` writes a 64-byte SHA-512 result through the `Preauth_HashValue` pointer read out of the freed object, giving a controlled kernel write once the slab is sprayed; the freed `file_table`/`tree_conns`/`user` fields additionally allow type confusion and control-flow hijacking.\nA:H - Even without successful exploitation the use-after-free dereferences freed slab memory and corrupts the allocator, producing kernel oopses and panics that take down the SMB server host, and it can be retriggered at will." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/server/mgmt/user_session.c", "fs/smb/server/mgmt/user_session.h", "fs/smb/server/server.c", "fs/smb/server/smb2pdu.c" ], "versions": [ { "version": "0626e6641f6b467447c81dd7678a69c66f7746cf", "lessThan": "0f62358ce85b2d4c949ef1b648be01b29cec667a", "status": "affected", "versionType": "git" }, { "version": "0626e6641f6b467447c81dd7678a69c66f7746cf", "lessThan": "a9839c37fd813b432988f58a9d9dd59253d3eb2c", "status": "affected", "versionType": "git" }, { "version": "0626e6641f6b467447c81dd7678a69c66f7746cf", "lessThan": "5511999e9615e4318e9142d23b29bd1597befc08", "status": "affected", "versionType": "git" }, { "version": "0626e6641f6b467447c81dd7678a69c66f7746cf", "lessThan": "ee371898b53a9b9b51c02d22a8c31bfb86d45f0d", "status": "affected", "versionType": "git" }, { "version": "0626e6641f6b467447c81dd7678a69c66f7746cf", "lessThan": "7aa8804c0b67b3cb263a472d17f2cb50d7f1a930", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/server/mgmt/user_session.c", "fs/smb/server/mgmt/user_session.h", "fs/smb/server/server.c", "fs/smb/server/smb2pdu.c" ], "versions": [ { "version": "5.15", "status": "affected" }, { "version": "0", "lessThan": "5.15", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.171", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.114", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.58", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.11.5", "lessThanOrEqual": "6.11.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12", "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": "5.15", "versionEndExcluding": "5.15.171" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.1.114" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.6.58" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.11.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.12" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/0f62358ce85b2d4c949ef1b648be01b29cec667a" }, { "url": "https://git.kernel.org/stable/c/a9839c37fd813b432988f58a9d9dd59253d3eb2c" }, { "url": "https://git.kernel.org/stable/c/5511999e9615e4318e9142d23b29bd1597befc08" }, { "url": "https://git.kernel.org/stable/c/ee371898b53a9b9b51c02d22a8c31bfb86d45f0d" }, { "url": "https://git.kernel.org/stable/c/7aa8804c0b67b3cb263a472d17f2cb50d7f1a930" } ], "title": "ksmbd: fix user-after-free from session log off", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "cvssV3_1": { "scope": "UNCHANGED", "version": "3.1", "baseScore": 7.8, "attackVector": "LOCAL", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "HIGH" } }, { "other": { "type": "ssvc", "content": { "id": "CVE-2024-50086", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "total" } ], "version": "2.0.3", "timestamp": "2025-04-25T14:30:09.987767Z" } } } ], "problemTypes": [ { "descriptions": [ { "lang": "en", "type": "CWE", "cweId": "CWE-416", "description": "CWE-416 Use After Free" } ] } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2025-04-25T14:36:34.763Z" } }, { "title": "CVE Program Container", "references": [ { "url": "https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T22:25:18.791Z" } } ] } }