{ "schema_version": "1.6.1", "id": "RPI-CVE-2023-53338", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2023-53338" ], "published": "2025-09-17T14:57:20Z", "summary": "lwt: Fix return values of BPF xmit ops", "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nlwt: Fix return values of BPF xmit ops\n\nBPF encap ops can return different types of positive values, such like\nNET_RX_DROP, NET_XMIT_CN, NETDEV_TX_BUSY, and so on, from function\nskb_do_redirect and bpf_lwt_xmit_reroute. At the xmit hook, such return\nvalues would be treated implicitly as LWTUNNEL_XMIT_CONTINUE in\nip(6)_finish_output2. When this happens, skbs that have been freed would\ncontinue to the neighbor subsystem, causing use-after-free bug and\nkernel crashes.\n\nTo fix the incorrect behavior, skb_do_redirect return values can be\nsimply discarded, the same as tc-egress behavior. On the other hand,\nbpf_lwt_xmit_reroute returns useful errors to local senders, e.g. PMTU\ninformation. Thus convert its return values to avoid the conflict with\nLWTUNNEL_XMIT_CONTINUE.", "severity": [ { "type": "CVSS_V3", "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H" } ], "affected": [ { "package": { "ecosystem": "Raspberry Pi OS:12", "name": "linux" }, "versions": [ "1:6.1.21-1+rpt1", "1:6.1.47-1+rpt2", "1:6.1.47-1+rpt4" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.1.0-rpi1-rpi-v6", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi1-rpi-v7", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi1-rpi-v7l", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi1-rpi-v8", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi2-rpi-v6", "binary_version": "1:6.1.47-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi2-rpi-v7", "binary_version": "1:6.1.47-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi2-rpi-v7l", "binary_version": "1:6.1.47-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi2-rpi-v8", "binary_version": "1:6.1.47-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-2712", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v6", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v7", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v8", "binary_version": "1:6.1.47-1+rpt4" } ] }, "database_specific": { "per_version": { "1:6.1.21-1+rpt1": { "linux_commit": "0afb5e98488aed7017b9bf321b575d0177feb7ed", "upstream_version": "6.1.21", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.53" }, "1:6.1.47-1+rpt2": { "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e", "upstream_version": "6.1.47", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.53" }, "1:6.1.47-1+rpt4": { "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e", "upstream_version": "6.1.47", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.53", "compiled_filter": false } } } } ], "references": [ { "type": "ADVISORY", "url": "https://www.cve.org/CVERecord?id=CVE-2023-53338" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/67f8f2bae8e7ac72e09def2b667e44704c4d1ee1" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/a97f221651fcdc891166e9bc270e3d9bfa5a0080" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/e3f647e4b642f9f6d32795a16f92c116c138d2af" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/065d5f17096ec9161180e2c890afdff4dc6125f2" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/d68c17402442f5f494a2c3ebde5cb82f6aa9160a" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/65583f9e070db7bece20710cfa2e3daeb0b831d9" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/29b22badb7a84b783e3a4fffca16f7768fb31205" } ], "database_specific": { "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git", "upstream_modified": "2026-08-05T11:24:39Z", "severity": { "source": "kernel CNA", "cvss_v3_score": 9.8, "cvss_v3_severity": "Critical", "scenario": "AV:N - On hosts with LWT BPF xmit routes (e.g. edge/CDN forwarders), remote packets that are forwarded or that induce local replies reach ip(6)_finish_output2 \u2192 lwtunnel_xmit \u2192 bpf_xmit, so an unauthenticated network peer drives the vulnerable path.\nAC:L - LWT BPF xmit programs routinely return BPF_REDIRECT or BPF_LWT_REROUTE; skb_do_redirect/dst_output then yield positive NET_XMIT_*/NETDEV_TX_* statuses (e.g. NET_XMIT_CN under load) that the attacker can provoke by sending traffic, with no condition outside their control.\nPR:N - Once an LWT BPF xmit route is configured, no credentials are required\u2014any remote peer whose packets traverse that route reaches the bug; local unprivileged traffic generation likewise needs no elevated privileges.\nUI:N - Exploitation requires only attacker-generated traffic against an already-configured LWT BPF route; no victim or administrator action is needed at exploit time.\nS:U - The use-after-free and any resulting privilege escalation remain within the host kernel's security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The bug is a use-after-free of a consumed skb that continues into the neighbor subsystem; reclaiming and spraying that object enables arbitrary kernel memory disclosure.\nI:H - The same skb UAF in neigh_output provides heap corruption suitable for arbitrary write and control-flow hijack, i.e. full kernel integrity compromise.\nA:H - Continuing a freed skb into neigh_output reliably causes kernel oops/panic, as documented in the fix and reproduced by the LWT redirect selftests." } } }