{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2024-26996", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-02-19T14:20:24.206Z", "datePublished": "2024-05-01T05:28:16.652Z", "dateUpdated": "2026-08-05T11:28:54.861Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:28:54.861Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nusb: gadget: f_ncm: Fix UAF ncm object at re-bind after usb ep transport error\n\nWhen ncm function is working and then stop usb0 interface for link down,\neth_stop() is called. At this piont, accidentally if usb transport error\nshould happen in usb_ep_enable(), 'in_ep' and/or 'out_ep' may not be enabled.\n\nAfter that, ncm_disable() is called to disable for ncm unbind\nbut gether_disconnect() is never called since 'in_ep' is not enabled.\n\nAs the result, ncm object is released in ncm unbind\nbut 'dev->port_usb' associated to 'ncm->port' is not NULL.\n\nAnd when ncm bind again to recover netdev, ncm object is reallocated\nbut usb0 interface is already associated to previous released ncm object.\n\nTherefore, once usb0 interface is up and eth_start_xmit() is called,\nreleased ncm object is dereferrenced and it might cause use-after-free memory.\n\n[function unlink via configfs]\n usb0: eth_stop dev->port_usb=ffffff9b179c3200\n --> error happens in usb_ep_enable().\n NCM: ncm_disable: ncm=ffffff9b179c3200\n --> no gether_disconnect() since ncm->port.in_ep->enabled is false.\n NCM: ncm_unbind: ncm unbind ncm=ffffff9b179c3200\n NCM: ncm_free: ncm free ncm=ffffff9b179c3200 <-- released ncm\n\n[function link via configfs]\n NCM: ncm_alloc: ncm alloc ncm=ffffff9ac4f8a000\n NCM: ncm_bind: ncm bind ncm=ffffff9ac4f8a000\n NCM: ncm_set_alt: ncm=ffffff9ac4f8a000 alt=0\n usb0: eth_open dev->port_usb=ffffff9b179c3200 <-- previous released ncm\n usb0: eth_start dev->port_usb=ffffff9b179c3200 <--\n eth_start_xmit()\n --> dev->wrap()\n Unable to handle kernel paging request at virtual address dead00000000014f\n\nThis patch addresses the issue by checking if 'ncm->netdev' is not NULL at\nncm_disable() to call gether_disconnect() to deassociate 'dev->port_usb'.\nIt's more reasonable to check 'ncm->netdev' to call gether_connect/disconnect\nrather than check 'ncm->port.in_ep->enabled' since it might not be enabled\nbut the gether connection might be established." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - Every step needed to reach and trigger the dangling `dev->port_usb` is a local operation — configfs gadget function unlink/relink, `ip link set usb0 down/up`, and a packet transmit on usb0 that reaches `eth_start_xmit()`/`dev->wrap()`. No physical USB host interaction is required for the freed `f_ncm` to be dereferenced, and on dummy_hcd-style setups even the host side is driven locally.\nAC:L - The attacker drives both sides of the sequence and can repeat it indefinitely (loop link down/up plus function unlink/relink), and the `eth_stop()` path that leaves `in_ep` disabled while the gether link stays associated is reachable via the carrier window in `gether_connect()` as well as any `usb_ep_enable()` failure. Freed-object reclaim of a plain kmalloc slab is standard and reliable.\nPR:L - The gadget/netdev reconfiguration is administrative, but on the affected NCM/tethering deployments those interfaces are delegated to low-privilege system components and the netdev can live in a delegated netns where CAP_NET_ADMIN is obtainable via user namespaces; the final use-after-free dereference in `eth_start_xmit()` is reached by any unprivileged local user simply sending traffic on usb0.\nUI:N - No action by another user is required — the attacker performs the whole sequence, and once the interface is brought up the stale pointer is dereferenced automatically by IPv6 DAD/RA or any queued transmit.\nS:U - The use-after-free is confined to kernel memory in the same security authority; there is no VM, IOMMU, or sandbox boundary crossed.\nC:H - The freed `f_ncm` is reached through `dev->port_usb` and its fields (`parser_opts`, `cdc_filter`, `skb_tx_data/ndp`, `fixed_in_len`) are used for length arithmetic and buffer construction in `ncm_wrap_ntb`, so a reclaimed slab gives an attacker-controlled read primitive and kernel memory disclosure through transmitted frames.\nI:H - `eth_open()` performs `link->open(link)` — an indirect call through a function pointer stored inside the freed object — and `ncm_wrap_ntb` writes using attacker-controlled offsets from the reclaimed allocation, providing arbitrary write and control-flow hijack suitable for privilege escalation.\nA:H - The commit log documents the resulting kernel oops (\"Unable to handle kernel paging request at virtual address dead00000000014f\"); any unmitigated dereference of the freed ncm object panics the kernel." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/usb/gadget/function/f_ncm.c" ], "versions": [ { "version": "6b4012a2e4d4702f8fb0ee1db1c0f0b17ab7d41b", "lessThan": "7f67c2020cb08499c400abf0fc32c65e4d9a09ca", "status": "affected", "versionType": "git" }, { "version": "6b4012a2e4d4702f8fb0ee1db1c0f0b17ab7d41b", "lessThan": "0588bbbd718a8130b98c54518f1e0b569ce60a93", "status": "affected", "versionType": "git" }, { "version": "6b4012a2e4d4702f8fb0ee1db1c0f0b17ab7d41b", "lessThan": "f356fd0cbd9c9cbd0854657a80d1608d0d732db3", "status": "affected", "versionType": "git" }, { "version": "6b4012a2e4d4702f8fb0ee1db1c0f0b17ab7d41b", "lessThan": "7250326cbb1f4f90391ac511a126b936cefb5bb7", "status": "affected", "versionType": "git" }, { "version": "6b4012a2e4d4702f8fb0ee1db1c0f0b17ab7d41b", "lessThan": "6334b8e4553cc69f51e383c9de545082213d785e", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/usb/gadget/function/f_ncm.c" ], "versions": [ { "version": "4.4", "status": "affected" }, { "version": "0", "lessThan": "4.4", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.157", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.88", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.29", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.8.8", "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": "4.4", "versionEndExcluding": "5.15.157" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.4", "versionEndExcluding": "6.1.88" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.4", "versionEndExcluding": "6.6.29" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.4", "versionEndExcluding": "6.8.8" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.4", "versionEndExcluding": "6.9" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/7f67c2020cb08499c400abf0fc32c65e4d9a09ca" }, { "url": "https://git.kernel.org/stable/c/0588bbbd718a8130b98c54518f1e0b569ce60a93" }, { "url": "https://git.kernel.org/stable/c/f356fd0cbd9c9cbd0854657a80d1608d0d732db3" }, { "url": "https://git.kernel.org/stable/c/7250326cbb1f4f90391ac511a126b936cefb5bb7" }, { "url": "https://git.kernel.org/stable/c/6334b8e4553cc69f51e383c9de545082213d785e" } ], "title": "usb: gadget: f_ncm: Fix UAF ncm object at re-bind after usb ep transport error", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2024-26996", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "version": "2.0.3", "timestamp": "2024-05-10T18:35:08.216292Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2024-07-05T17:22:50.015Z" } }, { "title": "CVE Program Container", "references": [ { "url": "https://git.kernel.org/stable/c/7f67c2020cb08499c400abf0fc32c65e4d9a09ca", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/0588bbbd718a8130b98c54518f1e0b569ce60a93", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/f356fd0cbd9c9cbd0854657a80d1608d0d732db3", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/7250326cbb1f4f90391ac511a126b936cefb5bb7", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/6334b8e4553cc69f51e383c9de545082213d785e", "tags": [ "x_transferred" ] }, { "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/DAMSOZXJEPUOXW33WZYWCVAY7Z5S7OOY/" }, { "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/4EZ6PJW7VOZ224TD7N4JZNU6KV32ZJ53/" }, { "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/GCBZZEC7L7KTWWAS2NLJK6SO3IZIL4WW/" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-04T17:16:00.909Z" } } ] } }