{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-72057", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-09T03:40:39.903Z", "datePublished": "2026-08-15T05:52:12.873Z", "dateUpdated": "2026-08-23T12:46:36.427Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-23T12:46:36.427Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: act_ct: preserve tc_skb_cb across defragmentation\n\ntcf_ct_handle_fragments() calls nf_ct_handle_fragments() without saving\nand restoring skb->cb. The defrag helper clears IPCB/IP6CB, which aliases\nthe tc_skb_cb/qdisc_skb_cb control buffer. Fragmented traffic through\nact_ct therefore loses qdisc metadata such as pkt_segs and can trigger\nWARN_ON_ONCE() in qdisc_pkt_segs() when panic_on_warn is enabled.\n\nSave and restore the full tc_skb_cb around nf_ct_handle_fragments(),\nmatching the pattern used by ovs_ct_handle_fragments()." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H", "baseScore": 8.2, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - The bug fires in tcf_ct_act() on the packet datapath (sch_handle_ingress/egress → tc_run → tcf_classify) when IP fragments arrive; on OVN/Kubernetes/SDN gateways and mlx5 offload nodes with act_ct already installed, a remote peer triggers it by sending fragmented traffic with no local access.\nAC:L - The attacker fully controls fragment boundaries and ordering; nf_ct_handle_fragments() memset of IPCB/IP6CB that aliases tc_skb_cb runs deterministically on each matching fragment through the configured ct action without races or memory-layout dependencies.\nPR:N - Installing act_ct requires CAP_NET_ADMIN, but triggering the bug on an already-configured internet-facing or tenant-facing gateway needs no target credentials; a remote attacker only sends crafted IP fragments, matching CNA precedent for packet-driven act_ct issues (e.g., CVE-2023-52610).\nUI:N - Exploitation requires only attacker-generated fragmented packets reaching a host with act_ct on clsact/ingress; no victim login, mount, or other interactive action is needed.\nS:U - WARN/panic and corrupted qdisc/tc metadata occur entirely within the host kernel security domain; this is not a VM escape, sandbox breakout, or IOMMU boundary bypass.\nC:N - memset(IPCB/IP6CB) zeroes tc_skb_cb/qdisc_skb_cb fields in place without out-of-bounds read or use-after-free; no kernel memory contents are disclosed to the attacker, only skb control-block metadata is clobbered.\nI:L - Clearing pkt_segs, pkt_len, post_ct, and zone corrupts tc/qdisc state consumed by bstats_update, sch_cake/sch_qfq, and cls_flower zone matching, enabling attacker-driven mis-accounting and mis-handling of packets on the affected path.\nA:H - Zeroed pkt_segs makes qdisc_pkt_segs() hit DEBUG_NET_WARN_ON_ONCE when it disagrees with GSO segment count; with panic_on_warn enabled this kernel-panics the host, and the condition is repeatable with sustained fragmented traffic." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/sched/act_ct.c" ], "versions": [ { "version": "0d76daf2013ce1da20eab5e26bd81d983e1c18fb", "lessThan": "fb080b6f54835d5d4d11ce3122800e6f0f6689e6", "status": "affected", "versionType": "git" }, { "version": "ec624fe740b416fb68d536b37fb8eef46f90b5c2", "lessThan": "67d6b00a54446c008f52cf70fc0c2ad0c712f85d", "status": "affected", "versionType": "git" }, { "version": "ec624fe740b416fb68d536b37fb8eef46f90b5c2", "lessThan": "2400c4b05d58834b994500a9eec90a37db44187c", "status": "affected", "versionType": "git" }, { "version": "ec624fe740b416fb68d536b37fb8eef46f90b5c2", "lessThan": "5c3ae5f6c7c6de73ea9b6a75154fe4ed343e1bac", "status": "affected", "versionType": "git" }, { "version": "ec624fe740b416fb68d536b37fb8eef46f90b5c2", "lessThan": "b3d835407846134b0d54637c0281b39bebef831d", "status": "affected", "versionType": "git" }, { "version": "ec624fe740b416fb68d536b37fb8eef46f90b5c2", "lessThan": "f7f45ceb855d9ba1cba594fb3f383255f7013fad", "status": "affected", "versionType": "git" }, { "version": "ec624fe740b416fb68d536b37fb8eef46f90b5c2", "lessThan": "9092e15defbe6c7bc241c306093ca9d358a578e7", "status": "affected", "versionType": "git" }, { "version": "5.15.13", "lessThan": "5.15.217", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/sched/act_ct.c" ], "versions": [ { "version": "5.16", "status": "affected" }, { "version": "0", "lessThan": "5.16", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.217", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.184", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.145", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.97", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.40", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.5", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "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": "5.15.13", "versionEndExcluding": "5.15.217" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.16", "versionEndExcluding": "6.1.184" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.16", "versionEndExcluding": "6.6.145" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.16", "versionEndExcluding": "6.12.97" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.16", "versionEndExcluding": "6.18.40" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.16", "versionEndExcluding": "7.1.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.16", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/fb080b6f54835d5d4d11ce3122800e6f0f6689e6" }, { "url": "https://git.kernel.org/stable/c/67d6b00a54446c008f52cf70fc0c2ad0c712f85d" }, { "url": "https://git.kernel.org/stable/c/2400c4b05d58834b994500a9eec90a37db44187c" }, { "url": "https://git.kernel.org/stable/c/5c3ae5f6c7c6de73ea9b6a75154fe4ed343e1bac" }, { "url": "https://git.kernel.org/stable/c/b3d835407846134b0d54637c0281b39bebef831d" }, { "url": "https://git.kernel.org/stable/c/f7f45ceb855d9ba1cba594fb3f383255f7013fad" }, { "url": "https://git.kernel.org/stable/c/9092e15defbe6c7bc241c306093ca9d358a578e7" } ], "title": "net/sched: act_ct: preserve tc_skb_cb across defragmentation", "x_generator": { "engine": "bippy-1.2.0" } } } }