{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-72422","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-08-09T03:40:39.927Z","datePublished":"2026-08-15T05:56:41.090Z","dateUpdated":"2026-08-17T05:44:02.758Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-17T05:44:02.758Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix use-after-free of conn->preauth_info in concurrent SMB2 NEGOTIATE\n\nconn->preauth_info is shared connection state (struct\npreauth_integrity_info, kmalloc-96) that is allocated and freed by the\nSMB2 NEGOTIATE handler and read by the response send path.\n\nsmb2_handle_negotiate() allocates conn->preauth_info, and on a\ndeassemble_neg_contexts() failure kfrees it and sets it to NULL. Both the\nallocation and the free/NULL happen under ksmbd_conn_lock(conn) (the\nconnection srv_mutex), which is held across the whole handler body.\n\nThe response send path smb3_preauth_hash_rsp(), called from the send:\nblock of __handle_ksmbd_work(), reads conn->preauth_info and dereferences\nconn->preauth_info->Preauth_HashValue (via\nksmbd_gen_preauth_integrity_hash()) without taking conn_lock. When a\nclient drives two SMB2 NEGOTIATE requests on the same connection, one\nworker can free conn->preauth_info on the failing-negotiate path while a\nconcurrent send-path worker is reading it, producing a slab\nuse-after-free read (KASAN-confirmed).\n\nThe send-path read tested conn->preauth_info for NULL but raced with the\nfree that occurs between the NULL check and the dereference, so the NULL\nguard alone does not close the window.\n\nSerialize the NEGOTIATE-branch read in smb3_preauth_hash_rsp() under\nksmbd_conn_lock(conn) and re-check conn->preauth_info inside the lock.\nBecause the negotiate handler holds conn_lock across its kfree + NULL\nassignment, a reader that also takes conn_lock either runs fully before\nthe allocation or fully after the NULL store, and can never observe the\nfreed-but-not-yet-NULLed pointer. ksmbd_gen_preauth_integrity_hash()\ntakes no locks itself (it only computes a SHA-512 over the buffer), so\nno lock-ordering inversion is introduced, and conn_lock is a sleepable\nmutex which is safe on this send path (it already performs network I/O)."}],"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 bug is in ksmbd's SMB2 NEGOTIATE handler reachable by any remote client over TCP port 445 without local access; exploitation requires only crafted SMB 3.1.1 negotiate packets on an established network connection.\nAC:L - The attacker controls both sides of the race by pipelining two SMB2 NEGOTIATE requests on the same connection, with one crafted to fail deassemble_neg_contexts() and free preauth_info while the other is in the response send path; KASAN-confirmed UAF with no uncontrollable timing.\nPR:N - SMB2 NEGOTIATE is processed before any authentication or session establishment; smb2_check_user_session explicitly exempts NEGOTIATE from session validation, so an unauthenticated remote attacker can reach the vulnerable code path.\nUI:N - Exploitation requires only network packets sent by the attacker to an exposed ksmbd instance; no victim user action such as mounting a share or opening a file is needed.\nS:U - Successful exploitation compromises kernel memory on the SMB server host itself; this is standard in-kernel memory corruption without crossing a VM, container, or IOMMU security boundary to a separate authority.\nC:H - KASAN-confirmed slab use-after-free read of conn->preauth_info (kmalloc-96) via Preauth_HashValue and Preauth_HashId dereference; UAF on attacker-influenced freed heap memory enables arbitrary kernel memory disclosure through heap grooming.\nI:H - The UAF corrupts kernel heap state on a network-facing pre-auth path; freed preauth_integrity_info objects can be reallocated via heap spraying to obtain arbitrary write or control-flow hijack primitives beyond the immediate hash-buffer access.\nA:H - Concurrent UAF read of freed conn->preauth_info during smb3_preauth_hash_rsp() causes kernel oops or panic (KASAN-confirmed); even without full exploitation the race reliably triggers high-severity denial of service on the server."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/server/smb2pdu.c"],"versions":[{"version":"dd4e4c811898410e6a3ae3b63207b7c542860907","lessThan":"c7bef84740d1d57848c74f6f5b996606e43ea4fe","status":"affected","versionType":"git"},{"version":"aa7253c2393f6dcd6a1468b0792f6da76edad917","lessThan":"d0a469122e7bf8338fec1949fb1e8e1290ed8caa","status":"affected","versionType":"git"},{"version":"aa7253c2393f6dcd6a1468b0792f6da76edad917","lessThan":"7470511d085af1c7a043a60e53d52b512d5a10b1","status":"affected","versionType":"git"},{"version":"aa7253c2393f6dcd6a1468b0792f6da76edad917","lessThan":"16a1ecf39c217e3d164bd32ef2a4f650abc067fa","status":"affected","versionType":"git"},{"version":"aa7253c2393f6dcd6a1468b0792f6da76edad917","lessThan":"77bb0bbfcc4e777ca653174689e5e363f8ee63d1","status":"affected","versionType":"git"},{"version":"aa7253c2393f6dcd6a1468b0792f6da76edad917","lessThan":"1c89da3baa2b1f269178afa87dc30479b8535776","status":"affected","versionType":"git"},{"version":"aa7253c2393f6dcd6a1468b0792f6da76edad917","lessThan":"0c054227479ed7e36ebccb3a558bc0ef698264f6","status":"affected","versionType":"git"},{"version":"8a8315a5960bd2b5ffc75f44fc089e57c3b17c44","status":"affected","versionType":"git"},{"version":"ff20f1875889dbe4a67c9298e609d7c88cf6456d","status":"affected","versionType":"git"},{"version":"5.15.61","lessThan":"5.15.212","status":"affected","versionType":"semver"},{"version":"5.18.18","lessThan":"5.19","status":"affected","versionType":"semver"},{"version":"5.19.2","lessThan":"5.20","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/smb2pdu.c"],"versions":[{"version":"6.0","status":"affected"},{"version":"0","lessThan":"6.0","status":"unaffected","versionType":"semver"},{"version":"5.15.212","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.178","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.145","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.97","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.40","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.1.5","lessThanOrEqual":"7.1.*","status":"unaffected","versionType":"semver"},{"version":"7.2","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":"5.15.61","versionEndExcluding":"5.15.212"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.0","versionEndExcluding":"6.1.178"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.0","versionEndExcluding":"6.6.145"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.0","versionEndExcluding":"6.12.97"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.0","versionEndExcluding":"6.18.40"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.0","versionEndExcluding":"7.1.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.0","versionEndExcluding":"7.2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.18.18"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19.2"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/c7bef84740d1d57848c74f6f5b996606e43ea4fe"},{"url":"https://git.kernel.org/stable/c/d0a469122e7bf8338fec1949fb1e8e1290ed8caa"},{"url":"https://git.kernel.org/stable/c/7470511d085af1c7a043a60e53d52b512d5a10b1"},{"url":"https://git.kernel.org/stable/c/16a1ecf39c217e3d164bd32ef2a4f650abc067fa"},{"url":"https://git.kernel.org/stable/c/77bb0bbfcc4e777ca653174689e5e363f8ee63d1"},{"url":"https://git.kernel.org/stable/c/1c89da3baa2b1f269178afa87dc30479b8535776"},{"url":"https://git.kernel.org/stable/c/0c054227479ed7e36ebccb3a558bc0ef698264f6"}],"title":"ksmbd: fix use-after-free of conn->preauth_info in concurrent SMB2 NEGOTIATE","x_generator":{"engine":"bippy-1.2.0"}}}}