{"api_version":"1","generated_at":"2026-10-18T07:54:21+00:00","cve":"CVE-2026-98173","urls":{"html":"https://cve.report/CVE-2026-98173","api":"https://cve.report/api/cve/CVE-2026-98173.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-98173","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-98173"},"summary":{"title":"smb: client: fix use-after-free of iface in cifs_try_adding_channels()","description":"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.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-10-06 09:17:59","updated_at":"2026-10-07 07:17:03"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.5","severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H","data":{"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","attackVector":"NETWORK","attackComplexity":"HIGH","privilegesRequired":"NONE","userInteraction":"REQUIRED","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.5","severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H","data":{"baseScore":7.5,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/ec36b38e65596950e6c29bed7dfc90b98707c19c","name":"https://git.kernel.org/stable/c/ec36b38e65596950e6c29bed7dfc90b98707c19c","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/e99040e5e9c60441e6b4725e1a7b88c3106ae903","name":"https://git.kernel.org/stable/c/e99040e5e9c60441e6b4725e1a7b88c3106ae903","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/c941f1ebfd26f683de81091473f3596a218abff0","name":"https://git.kernel.org/stable/c/c941f1ebfd26f683de81091473f3596a218abff0","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/d034e836eefd7ce75e588f7031cffbeec594f5ac","name":"https://git.kernel.org/stable/c/d034e836eefd7ce75e588f7031cffbeec594f5ac","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-98173","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98173","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected aa45dadd34e44fcd6a9df4b395bee5b5633b4cec c941f1ebfd26f683de81091473f3596a218abff0 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected aa45dadd34e44fcd6a9df4b395bee5b5633b4cec e99040e5e9c60441e6b4725e1a7b88c3106ae903 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected aa45dadd34e44fcd6a9df4b395bee5b5633b4cec ec36b38e65596950e6c29bed7dfc90b98707c19c git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected aa45dadd34e44fcd6a9df4b395bee5b5633b4cec d034e836eefd7ce75e588f7031cffbeec594f5ac git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.19","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.19 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.112 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.54 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.8 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc4 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"98173","cve":"CVE-2026-98173","epss":"0.002090000","percentile":"0.100300000","score_date":"2026-10-06","updated_at":"2026-10-07 00:14:55"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/smb/client/sess.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"c941f1ebfd26f683de81091473f3596a218abff0","status":"affected","version":"aa45dadd34e44fcd6a9df4b395bee5b5633b4cec","versionType":"git"},{"lessThan":"e99040e5e9c60441e6b4725e1a7b88c3106ae903","status":"affected","version":"aa45dadd34e44fcd6a9df4b395bee5b5633b4cec","versionType":"git"},{"lessThan":"ec36b38e65596950e6c29bed7dfc90b98707c19c","status":"affected","version":"aa45dadd34e44fcd6a9df4b395bee5b5633b4cec","versionType":"git"},{"lessThan":"d034e836eefd7ce75e588f7031cffbeec594f5ac","status":"affected","version":"aa45dadd34e44fcd6a9df4b395bee5b5633b4cec","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/smb/client/sess.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"5.19"},{"lessThan":"5.19","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.112","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.54","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.8","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc4","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.112","versionStartIncluding":"5.19","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.54","versionStartIncluding":"5.19","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.8","versionStartIncluding":"5.19","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc4","versionStartIncluding":"5.19","vulnerable":true}],"negate":false,"operator":"OR"}]}],"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":{"baseScore":7.5,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H","version":"3.1"},"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."}]}],"providerMetadata":{"dateUpdated":"2026-10-07T06:49:22.240Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"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"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-98173","datePublished":"2026-10-06T08:44:17.567Z","dateReserved":"2026-09-25T10:25:14.322Z","dateUpdated":"2026-10-07T06:49:22.240Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-10-06 09:17:59","lastModifiedDate":"2026-10-07 07:17:03","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"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","attackVector":"NETWORK","attackComplexity":"HIGH","privilegesRequired":"NONE","userInteraction":"REQUIRED","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.6,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"98173","Ordinal":"1","Title":"smb: client: fix use-after-free of iface in cifs_try_adding_chan","CVE":"CVE-2026-98173","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"98173","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"smb: client: fix use-after-free of iface in cifs_try_adding_chan"}]}}}