{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2023-53733", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-10-22T13:21:37.350Z", "datePublished": "2025-10-24T11:44:28.115Z", "dateUpdated": "2026-08-05T09:15:44.713Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T09:15:44.713Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: sched: cls_u32: Undo tcf_bind_filter if u32_replace_hw_knode\n\nWhen u32_replace_hw_knode fails, we need to undo the tcf_bind_filter\noperation done at u32_set_parms." } ], "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 - The vulnerable path is reached through the rtnetlink `RTM_NEWTFILTER` interface (tc filter add/change) on the local system; no network peer can drive filter configuration. Packet transmission only serves to consume the corrupted state afterwards.\nAC:L - Failure of `u32_replace_hw_knode()` is fully attacker-controlled — setting the `skip_sw` flag on a filter attached to a non-offload-capable device (dummy/veth/lo) makes `tc_setup_cb_add()` return `-EOPNOTSUPP` deterministically on every attempt, with no race and no dependence on state outside the attacker's control.\nPR:L - Only `CAP_NET_ADMIN` within a network namespace is needed, which any unprivileged local user obtains with `unshare -Urn` before creating a dummy device, an HTB qdisc with classes, and u32 filters. Per kernel CNA guidance, tc/qdisc paths reachable via user namespaces are PR:L, not PR:H.\nUI:N - The attacker performs the entire sequence (create qdisc/class, repeatedly issue the failing filter add, delete the class, send traffic) unaided. No victim action is required at any point.\nS:U - The corrupted `filter_cnt` accounting and the resulting freed `htb_class` object both live in the kernel of the same machine, so the impact stays within a single security authority. This is standard kernel-local privilege escalation, not a hypervisor or IOMMU boundary crossing.\nC:H - The refcount imbalance permits a still-referenced traffic class to be freed while `res.class` remains a dangling pointer consumed by `htb_classify()`, giving a use-after-free on a slab object the attacker can reallocate and read back. Per guidance, a UAF that grants control over freed-object contents is High confidentiality impact.\nI:H - The same use-after-free lets a sprayed replacement object supply `cl->level`, `cl->leaf.q` and the qdisc function pointers dereferenced in the enqueue path, yielding a write/control-flow-hijack primitive — the same primitive that produced working local privilege escalation for the sibling cls_u32 tcf_result bugs. Type-confused/UAF corruption of kernel objects is High integrity impact.\nA:H - Even without exploitation, the leaked `filter_cnt` permanently pins the class and its qdisc so `tc class del` always returns `-EBUSY` and the memory is never reclaimed, and the dangling `res.class` dereference in the packet enqueue path oopses the kernel. Any kernel crash or use-after-free is High availability impact." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/sched/cls_u32.c" ], "versions": [ { "version": "d34e3e181395192d6d1f50dd97bd7854e04e33a4", "lessThan": "a9345793469b65ee5ba7b033239916c2a67d3dd4", "status": "affected", "versionType": "git" }, { "version": "d34e3e181395192d6d1f50dd97bd7854e04e33a4", "lessThan": "025159ed118ba5145b241d574edadb0e00d3c20f", "status": "affected", "versionType": "git" }, { "version": "d34e3e181395192d6d1f50dd97bd7854e04e33a4", "lessThan": "9cb36faedeafb9720ac236aeae2ea57091d90a09", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/sched/cls_u32.c" ], "versions": [ { "version": "4.7", "status": "affected" }, { "version": "0", "lessThan": "4.7", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.42", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.4.7", "lessThanOrEqual": "6.4.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.5", "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": "4.7", "versionEndExcluding": "6.1.42" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.7", "versionEndExcluding": "6.4.7" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.7", "versionEndExcluding": "6.5" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/a9345793469b65ee5ba7b033239916c2a67d3dd4" }, { "url": "https://git.kernel.org/stable/c/025159ed118ba5145b241d574edadb0e00d3c20f" }, { "url": "https://git.kernel.org/stable/c/9cb36faedeafb9720ac236aeae2ea57091d90a09" } ], "title": "net: sched: cls_u32: Undo tcf_bind_filter if u32_replace_hw_knode", "x_generator": { "engine": "bippy-1.2.0" } } } }