{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2024-38538", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-06-18T19:36:34.918Z", "datePublished": "2024-06-19T13:35:13.384Z", "dateUpdated": "2026-08-05T11:32:37.537Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:32:37.537Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: bridge: xmit: make sure we have at least eth header len bytes\n\nsyzbot triggered an uninit value[1] error in bridge device's xmit path\nby sending a short (less than ETH_HLEN bytes) skb. To fix it check if\nwe can actually pull that amount instead of assuming.\n\nTested with dropwatch:\n drop at: br_dev_xmit+0xb93/0x12d0 [bridge] (0xffffffffc06739b3)\n origin: software\n timestamp: Mon May 13 11:31:53 2024 778214037 nsec\n protocol: 0x88a8\n length: 2\n original length: 2\n drop reason: PKT_TOO_SMALL\n\n[1]\nBUG: KMSAN: uninit-value in br_dev_xmit+0x61d/0x1cb0 net/bridge/br_device.c:65\n br_dev_xmit+0x61d/0x1cb0 net/bridge/br_device.c:65\n __netdev_start_xmit include/linux/netdevice.h:4903 [inline]\n netdev_start_xmit include/linux/netdevice.h:4917 [inline]\n xmit_one net/core/dev.c:3531 [inline]\n dev_hard_start_xmit+0x247/0xa20 net/core/dev.c:3547\n __dev_queue_xmit+0x34db/0x5350 net/core/dev.c:4341\n dev_queue_xmit include/linux/netdevice.h:3091 [inline]\n __bpf_tx_skb net/core/filter.c:2136 [inline]\n __bpf_redirect_common net/core/filter.c:2180 [inline]\n __bpf_redirect+0x14a6/0x1620 net/core/filter.c:2187\n ____bpf_clone_redirect net/core/filter.c:2460 [inline]\n bpf_clone_redirect+0x328/0x470 net/core/filter.c:2432\n ___bpf_prog_run+0x13fe/0xe0f0 kernel/bpf/core.c:1997\n __bpf_prog_run512+0xb5/0xe0 kernel/bpf/core.c:2238\n bpf_dispatcher_nop_func include/linux/bpf.h:1234 [inline]\n __bpf_prog_run include/linux/filter.h:657 [inline]\n bpf_prog_run include/linux/filter.h:664 [inline]\n bpf_test_run+0x499/0xc30 net/bpf/test_run.c:425\n bpf_prog_test_run_skb+0x14ea/0x1f20 net/bpf/test_run.c:1058\n bpf_prog_test_run+0x6b7/0xad0 kernel/bpf/syscall.c:4269\n __sys_bpf+0x6aa/0xd90 kernel/bpf/syscall.c:5678\n __do_sys_bpf kernel/bpf/syscall.c:5767 [inline]\n __se_sys_bpf kernel/bpf/syscall.c:5765 [inline]\n __x64_sys_bpf+0xa0/0xe0 kernel/bpf/syscall.c:5765\n x64_sys_call+0x96b/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:322\n do_syscall_x64 arch/x86/entry/common.c:52 [inline]\n do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83\n entry_SYSCALL_64_after_hwframe+0x77/0x7f" } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H", "baseScore": 7.3, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - `br_dev_xmit()` is the bridge device's locally-originated transmit path — remotely received frames go through `br_handle_frame`/`br_forward` and always carry a full Ethernet header, and IP routing toward a bridge always builds one via `dev_hard_header()`. Triggering it requires local injection of a sub-14-byte skb (tun write or AF_PACKET on a `hard_header_len == 0` device, plus a tc `mirred` redirect).\nAC:L - The attacker fully and deterministically controls the skb length; there is no race, no timing window, and no dependence on memory layout or victim state. Every attempt reaches the uninitialized read and the subsequent `skb_push()` leak.\nPR:L - The setup needs CAP_NET_ADMIN/CAP_NET_RAW only within a network namespace, which any unprivileged user obtains via `unshare -Urn` (create the bridge, create the tun/tunnel device, attach the tc mirred redirect, and capture leaked frames from a veth peer). No real root in the initial namespace is required.\nUI:N - The attacker performs every step — creating the devices, writing the short frame, and reading the leaked frames back — with no action by any other user or administrator.\nS:U - The uninitialized read, the malformed skb, and the resulting disclosure all stay within the kernel's own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - Up to 14 bytes of uninitialized kernel heap (skb headroom and the region past `skb->tail`, which routinely holds freed packet data and kernel values) are read and then, via the unconditional `skb_push(skb, ETH_HLEN)` in `br_dev_queue_push_xmit()`, transmitted verbatim out every bridge port where the attacker captures them. The leak is repeatable at packet rate, yielding an effectively unbounded kernel memory disclosure rather than a bounded few-byte read.\nI:L - There is no out-of-bounds write primitive, but the kernel emits malformed frames whose source/destination MAC addresses are uninitialized memory, and forwarding decisions (broadcast/multicast/unicast, FDB lookup) are made on that garbage — corrupting local and peer bridge/switch forwarding state in a limited, attacker-influenced way.\nA:H - When the short skb has less than ETH_HLEN of headroom (as in the syzbot BPF-redirect reproducer), `skb_push(skb, ETH_HLEN)` in `br_dev_queue_push_xmit()` drives `skb->data` below `skb->head` and hits `skb_under_panic()` → `BUG()`, a hard kernel panic. Additionally the resulting skb has `mac_header`/`network_header` desynchronized from `skb->data`, propagating a malformed skb into the generic xmit path (e.g. the `WARN_ONCE` in `skb_checksum_help()`, fatal under `panic_on_warn`), and the trigger can be repeated indefinitely." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/bridge/br_device.c" ], "versions": [ { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "3e01fc3c66e65d9afe98f1489047a1b2dd8741ca", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "b2b7c43cd32080221bb233741bd6011983fe7c11", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "82090f94c723dab724b1c32db406091d40448a17", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "c964429ef53f42098a6545a5dabeb1441c1e821d", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "28126b83f86ab9cc7936029c2dff845d3dcedba2", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "1abb371147905ba250b4cc0230c4be7e90bea4d5", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "f482fd4ce919836a49012b2d31b00fc36e2488f2", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "5b5d669f569807c7ab07546e73c0741845a2547a", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "8bd67ebb50c0145fd2ca8681ab65eb7e8cde1afc", "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/bridge/br_device.c" ], "versions": [ { "version": "2.6.12", "status": "affected" }, { "version": "0", "lessThan": "2.6.12", "status": "unaffected", "versionType": "semver" }, { "version": "4.19.324", "lessThanOrEqual": "4.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.4.286", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.230", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.172", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.93", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.33", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.8.12", "lessThanOrEqual": "6.8.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.9.3", "lessThanOrEqual": "6.9.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.10", "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": "2.6.12", "versionEndExcluding": "4.19.324" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "5.4.286" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "5.10.230" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "5.15.172" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.1.93" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.6.33" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.8.12" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.9.3" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.10" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/3e01fc3c66e65d9afe98f1489047a1b2dd8741ca" }, { "url": "https://git.kernel.org/stable/c/b2b7c43cd32080221bb233741bd6011983fe7c11" }, { "url": "https://git.kernel.org/stable/c/82090f94c723dab724b1c32db406091d40448a17" }, { "url": "https://git.kernel.org/stable/c/c964429ef53f42098a6545a5dabeb1441c1e821d" }, { "url": "https://git.kernel.org/stable/c/28126b83f86ab9cc7936029c2dff845d3dcedba2" }, { "url": "https://git.kernel.org/stable/c/1abb371147905ba250b4cc0230c4be7e90bea4d5" }, { "url": "https://git.kernel.org/stable/c/f482fd4ce919836a49012b2d31b00fc36e2488f2" }, { "url": "https://git.kernel.org/stable/c/5b5d669f569807c7ab07546e73c0741845a2547a" }, { "url": "https://git.kernel.org/stable/c/8bd67ebb50c0145fd2ca8681ab65eb7e8cde1afc" } ], "title": "net: bridge: xmit: make sure we have at least eth header len bytes", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "title": "CVE Program Container", "references": [ { "url": "https://git.kernel.org/stable/c/28126b83f86ab9cc7936029c2dff845d3dcedba2", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/1abb371147905ba250b4cc0230c4be7e90bea4d5", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/f482fd4ce919836a49012b2d31b00fc36e2488f2", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/5b5d669f569807c7ab07546e73c0741845a2547a", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/8bd67ebb50c0145fd2ca8681ab65eb7e8cde1afc", "tags": [ "x_transferred" ] }, { "url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T20:38:07.132Z" } }, { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2024-38538", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "version": "2.0.3", "timestamp": "2024-09-10T17:15:16.575973Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": 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