{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2024-35870", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-05-17T13:50:33.108Z", "datePublished": "2024-05-19T08:34:28.419Z", "dateUpdated": "2026-08-05T11:30:32.619Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:30:32.619Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix UAF in smb2_reconnect_server()\n\nThe UAF bug is due to smb2_reconnect_server() accessing a session that\nis already being teared down by another thread that is executing\n__cifs_put_smb_ses(). This can happen when (a) the client has\nconnection to the server but no session or (b) another thread ends up\nsetting @ses->ses_status again to something different than\nSES_EXITING.\n\nTo fix this, we need to make sure to unconditionally set\n@ses->ses_status to SES_EXITING and prevent any other threads from\nsetting a new status while we're still tearing it down.\n\nThe following can be reproduced by adding some delay to right after\nthe ipc is freed in __cifs_put_smb_ses() - which will give\nsmb2_reconnect_server() worker a chance to run and then accessing\n@ses->ipc:\n\nkinit ...\nmount.cifs //srv/share /mnt/1 -o sec=krb5,nohandlecache,echo_interval=10\n[disconnect srv]\nls /mnt/1 &>/dev/null\nsleep 30\nkdestroy\n[reconnect srv]\nsleep 10\numount /mnt/1\n...\nCIFS: VFS: Verify user has a krb5 ticket and keyutils is installed\nCIFS: VFS: \\\\srv Send error in SessSetup = -126\nCIFS: VFS: Verify user has a krb5 ticket and keyutils is installed\nCIFS: VFS: \\\\srv Send error in SessSetup = -126\ngeneral protection fault, probably for non-canonical address\n0x6b6b6b6b6b6b6b6b: 0000 [#1] PREEMPT SMP NOPTI\nCPU: 3 PID: 50 Comm: kworker/3:1 Not tainted 6.9.0-rc2 #1\nHardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-1.fc39\n04/01/2014\nWorkqueue: cifsiod smb2_reconnect_server [cifs]\nRIP: 0010:__list_del_entry_valid_or_report+0x33/0xf0\nCode: 4f 08 48 85 d2 74 42 48 85 c9 74 59 48 b8 00 01 00 00 00 00 ad\nde 48 39 c2 74 61 48 b8 22 01 00 00 00 00 74 69 <48> 8b 01 48 39 f8 75\n7b 48 8b 72 08 48 39 c6 0f 85 88 00 00 00 b8\nRSP: 0018:ffffc900001bfd70 EFLAGS: 00010a83\nRAX: dead000000000122 RBX: ffff88810da53838 RCX: 6b6b6b6b6b6b6b6b\nRDX: 6b6b6b6b6b6b6b6b RSI: ffffffffc02f6878 RDI: ffff88810da53800\nRBP: ffff88810da53800 R08: 0000000000000001 R09: 0000000000000000\nR10: 0000000000000000 R11: 0000000000000001 R12: ffff88810c064000\nR13: 0000000000000001 R14: ffff88810c064000 R15: ffff8881039cc000\nFS: 0000000000000000(0000) GS:ffff888157c00000(0000)\nknlGS:0000000000000000\nCS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 00007fe3728b1000 CR3: 000000010caa4000 CR4: 0000000000750ef0\nPKRU: 55555554\nCall Trace:\n \n ? die_addr+0x36/0x90\n ? exc_general_protection+0x1c1/0x3f0\n ? asm_exc_general_protection+0x26/0x30\n ? __list_del_entry_valid_or_report+0x33/0xf0\n __cifs_put_smb_ses+0x1ae/0x500 [cifs]\n smb2_reconnect_server+0x4ed/0x710 [cifs]\n process_one_work+0x205/0x6b0\n worker_thread+0x191/0x360\n ? __pfx_worker_thread+0x10/0x10\n kthread+0xe2/0x110\n ? __pfx_kthread+0x10/0x10\n ret_from_fork+0x34/0x50\n ? __pfx_kthread+0x10/0x10\n ret_from_fork_asm+0x1a/0x30\n " } ], "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 - The race is driven entirely by remote SMB server behavior — TCP disconnects, malformed/short responses, decryption failures, or withheld replies all reach `cifs_reconnect()` → `cifs_mark_tcp_ses_conns_for_reconnect()` from the demultiplex thread, and the freed tcon's contents are transmitted back over the network. A malicious/compromised SMB server or an on-path attacker against an existing CIFS mount exploits this remotely.\nAC:L - The attacker controls both sides: it triggers reconnect at will (RST/close/malformed frame) and observes the SMB2 LOGOFF request that `__cifs_put_smb_ses()` sends before blocking, giving an explicit on-wire marker for the teardown window, and the reconnect worker self-requeues every 2 s so the race can be retried indefinitely. In scenario (a) — server accepts TCP but fails SESSION_SETUP — `SES_EXITING` is never set at all, so no timing win is even required.\nPR:N - The attacker is the remote peer and needs no privileges or account on the victim client; valid SMB credentials are not required, since failed session setup is precisely what drives the vulnerable state.\nUI:N - The attack targets an already-established CIFS mount (fstab/autofs/Kubernetes-mounted shares on servers, NAS-backed embedded and industrial systems); reconnect and session teardown are triggered by the attacker and by background workers with no user action at attack time.\nS:U - Corruption is confined to kernel heap objects within the same security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The freed IPC `cifs_tcon` is re-read and `tcon->tree_name` is sent to the attacker-controlled server in the TREE_CONNECT, leaking reclaimed kernel heap contents directly to the attacker, and the freed `cifs_ses` holds session keys and `auth_key.response`; the UAF read primitive is unbounded.\nI:H - `cifs_smb_ses_inc_refcount()` writes to freed memory and `list_del_init(&ses->smb_ses_list)` performs a `prev->next = next` write through pointers read from a freed, sprayable kmalloc object — a write-what-where primitive suitable for control-flow hijack.\nA:H - The bug reproducibly causes a general protection fault in the cifsiod kworker (`__list_del_entry_valid_or_report` on 0x6b6b6b6b poison), killing the worker and panicking the system on `panic_on_oops` configurations." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/client/connect.c" ], "versions": [ { "version": "b327a717e506980399464e304e363f94f95eb7a1", "lessThan": "755fe68cd4b59e1d2a2dd3286177fd4404f57fed", "status": "affected", "versionType": "git" }, { "version": "b327a717e506980399464e304e363f94f95eb7a1", "lessThan": "6202996a1c1887e83d0b3b0fcd86d0e5e6910ea0", "status": "affected", "versionType": "git" }, { "version": "b327a717e506980399464e304e363f94f95eb7a1", "lessThan": "45f2beda1f1bc3d962ec07db1ccc3197c25499a5", "status": "affected", "versionType": "git" }, { "version": "b327a717e506980399464e304e363f94f95eb7a1", "lessThan": "24a9799aa8efecd0eb55a75e35f9d8e6400063aa", "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/client/connect.c" ], "versions": [ { "version": "4.16", "status": "affected" }, { "version": "0", "lessThan": "4.16", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.121", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.29", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.8.5", "lessThanOrEqual": "6.8.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.9", "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": "4.16", "versionEndExcluding": "6.1.121" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "6.6.29" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "6.8.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "6.9" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/755fe68cd4b59e1d2a2dd3286177fd4404f57fed" }, { "url": "https://git.kernel.org/stable/c/6202996a1c1887e83d0b3b0fcd86d0e5e6910ea0" }, { "url": "https://git.kernel.org/stable/c/45f2beda1f1bc3d962ec07db1ccc3197c25499a5" }, { "url": "https://git.kernel.org/stable/c/24a9799aa8efecd0eb55a75e35f9d8e6400063aa" } ], "title": "smb: client: fix UAF in smb2_reconnect_server()", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "problemTypes": [ { "descriptions": [ { "type": "CWE", "cweId": "CWE-416", "lang": "en", "description": "CWE-416 Use After Free" } ] } ], "metrics": [ { "cvssV3_1": { "scope": "UNCHANGED", "version": "3.1", "baseScore": 4.4, "attackVector": "LOCAL", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "HIGH", "confidentialityImpact": "HIGH" } }, { "other": { "type": "ssvc", "content": { "timestamp": "2024-06-17T17:38:54.896093Z", "id": "CVE-2024-35870", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "role": "CISA Coordinator", "version": "2.0.3" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2024-10-27T14:02:11.836Z" } }, { "title": "CVE Program Container", "references": [ { "url": "https://git.kernel.org/stable/c/6202996a1c1887e83d0b3b0fcd86d0e5e6910ea0", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/45f2beda1f1bc3d962ec07db1ccc3197c25499a5", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/24a9799aa8efecd0eb55a75e35f9d8e6400063aa", "tags": [ "x_transferred" ] }, { "url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T20:37:37.141Z" } } ] } }