{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-98173", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:25:14.322Z", "datePublished": "2026-10-06T08:44:17.567Z", "dateUpdated": "2026-10-21T12:54:49.437Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-21T12:54:49.437Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix use-after-free of iface in cifs_try_adding_channels()\n\ncifs_try_adding_channels() iterates ses->iface_list with\nlist_for_each_entry_safe_from(), which captures the next entry\n(niface) under iface_lock. The loop body then drops iface_lock for\nthe whole duration of cifs_ses_add_channel().\n\nA concurrent interface refresh (SMB3_request_interfaces() ->\nparse_server_interfaces()) marks all ifaces inactive and removes and\nfrees any that are not re-advertised via list_del() + kref_put(),\nwhere release_iface() is a bare kfree(). Since niface typically has\nno channel holding a reference, the list reference is its last and it\ncan be freed inside the unlocked window. On continue, the iterator\nadvance step then dereferences niface->iface_head.next, and the loop\nbody reads iface->rdma_capable/is_active, both on freed memory.\n\nFix this by never keeping an unreferenced list pointer across the\nunlocked window. Each channel attempt now re-scans the list from the\nhead under iface_lock, takes a kref on the selected candidate, and\npasses only that referenced candidate to cifs_ses_add_channel().\nweight_fulfilled still tracks selection progress, so restarting the\nscan preserves the original weighted distribution and the\nweight_fulfilled-before-kref_put ordering on the failure path.\n\nAdd a per-pass attempts cap so a flapping interface refresh cannot\nkeep the inner loop spinning within a single tries increment." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H", "baseScore": 7.5, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - A malicious SMB server sends the bad data over TCP/445 in its FSCTL_QUERY_NETWORK_INTERFACE_INFO responses. A later response leaves out an interface, so parse_server_interfaces() does list_del() and kref_put() and frees it. cifs_try_adding_channels() still holds niface after dropping iface_lock for cifs_ses_add_channel(), and that pointer now refers to freed memory.\nAC:H - Multichannel is off by default (multichannel=false, max_channels=1), so the victim must mount with multichannel or max_channels>1. The server also has to line up a refresh from the 600s smb2_query_server_interfaces worker with the unlocked add-channel window. It can stall channel setup and force reconnects to retry, but it does not schedule the worker.\nPR:N - The attacker only runs a rogue SMB server and needs no account or privilege on the victim client. The interface list is server-supplied data the client trusts during the session it opened.\nUI:R - A victim or admin has to mount a share from the attacker's server with multichannel turned on. CIFS mounts are not FS_USERNS_MOUNT, so the attacker cannot set up the client side alone.\nS:U - The memory corruption stays inside the client kernel's own security authority. No VM or other trust boundary is crossed.\nC:H - The loop continues through freed niface->iface_head.next and reads iface->rdma_capable, is_active, speed and sockaddr from the freed cifs_server_iface. The attacker can refill that heap object with their own data, which lets the kernel follow attacker-chosen pointers.\nI:H - Once the freed entry is reallocated, the loop does kref_get() and weight_fulfilled++/num_channels++ through the stale or forged iface pointer. That is a kernel write at a location the attacker influences, and cifs_ses_add_channel() then uses the forged object.\nA:H - Dereferencing the freed list entry in cifs_try_adding_channels() can oops or panic the client. The server can force reconnects to re-enter this path repeatedly." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/client/sess.c" ], "versions": [ { "version": "aa45dadd34e44fcd6a9df4b395bee5b5633b4cec", "lessThan": "ee0d8f83d68f6e6509f092c997ccab3c8c801538", "status": "affected", "versionType": "git" }, { "version": "aa45dadd34e44fcd6a9df4b395bee5b5633b4cec", "lessThan": "c941f1ebfd26f683de81091473f3596a218abff0", "status": "affected", "versionType": "git" }, { "version": "aa45dadd34e44fcd6a9df4b395bee5b5633b4cec", "lessThan": "e99040e5e9c60441e6b4725e1a7b88c3106ae903", "status": "affected", "versionType": "git" }, { "version": "aa45dadd34e44fcd6a9df4b395bee5b5633b4cec", "lessThan": "ec36b38e65596950e6c29bed7dfc90b98707c19c", "status": "affected", "versionType": "git" }, { "version": "aa45dadd34e44fcd6a9df4b395bee5b5633b4cec", "lessThan": "d034e836eefd7ce75e588f7031cffbeec594f5ac", "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/sess.c" ], "versions": [ { "version": "5.19", "status": "affected" }, { "version": "0", "lessThan": "5.19", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.160", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.112", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.54", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.8", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "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": "5.19", "versionEndExcluding": "6.6.160" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.12.112" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.18.54" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "7.2.8" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/ee0d8f83d68f6e6509f092c997ccab3c8c801538" }, { "url": "https://git.kernel.org/stable/c/c941f1ebfd26f683de81091473f3596a218abff0" }, { "url": "https://git.kernel.org/stable/c/e99040e5e9c60441e6b4725e1a7b88c3106ae903" }, { "url": "https://git.kernel.org/stable/c/ec36b38e65596950e6c29bed7dfc90b98707c19c" }, { "url": "https://git.kernel.org/stable/c/d034e836eefd7ce75e588f7031cffbeec594f5ac" } ], "title": "smb: client: fix use-after-free of iface in cifs_try_adding_channels()", "x_generator": { "engine": "bippy-1.2.0" } } } }