{"api_version":"1","generated_at":"2026-08-22T00:55:52+00:00","cve":"CVE-2026-72248","urls":{"html":"https://cve.report/CVE-2026-72248","api":"https://cve.report/api/cve/CVE-2026-72248.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-72248","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-72248"},"summary":{"title":"netfilter: flowtable: support IPIP tunnel with direct xmit","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: flowtable: support IPIP tunnel with direct xmit\n\nThe combination of IPIP tunnel with direct xmit, eg. bridge device,\nbreaks because no dst_entry is provided to check the skb headroom and to\nset the iph->frag_off field. This leads to invalid dst usage and can\ntrigger a crash in the tunnel transmit path.\n\nFix this by moving dst_cache and dst_cookie out of the runtime union so\nthat they can be shared by neighbour, xfrm, and direct tunnel flows.\nFor FLOW_OFFLOAD_XMIT_DIRECT tuples carrying tunnel metadata, preserve\nroute state in these shared fields and release it through the common\ndst release path.\n\nSince dst_entry is now available to the three supported xmit modes and\ndst_release() already deals with NULL dst, remove the xmit type check\nin nft_flow_dst_release(). Moreover, skip the check if the dst entry\nis NULL in nf_flow_dst_check() which is now the case for the direct\nxmit case.\n\nBased on patch from Rein Wei <n05ec@lzu.edu.cn>.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-08-15 06:21:52","updated_at":"2026-08-17 06:18:26"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"9.8","severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"9.8","severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":9.8,"baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/fa7395c02d95e51bad2952325d2d6503bfbad437","name":"https://git.kernel.org/stable/c/fa7395c02d95e51bad2952325d2d6503bfbad437","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/0880c4ed122d0cddc9f29a2b28f055d1f24f0fca","name":"https://git.kernel.org/stable/c/0880c4ed122d0cddc9f29a2b28f055d1f24f0fca","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-72248","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-72248","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected d30301ba4b07ac92eb38353a111833b009003170 0880c4ed122d0cddc9f29a2b28f055d1f24f0fca git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected d30301ba4b07ac92eb38353a111833b009003170 fa7395c02d95e51bad2952325d2d6503bfbad437 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.19","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.19 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.5 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"72248","cve":"CVE-2026-72248","epss":"0.005160000","percentile":"0.415090000","score_date":"2026-08-17","updated_at":"2026-08-18 00:11:47"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["include/net/netfilter/nf_flow_table.h","net/netfilter/nf_flow_table_core.c","net/netfilter/nf_flow_table_ip.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"0880c4ed122d0cddc9f29a2b28f055d1f24f0fca","status":"affected","version":"d30301ba4b07ac92eb38353a111833b009003170","versionType":"git"},{"lessThan":"fa7395c02d95e51bad2952325d2d6503bfbad437","status":"affected","version":"d30301ba4b07ac92eb38353a111833b009003170","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["include/net/netfilter/nf_flow_table.h","net/netfilter/nf_flow_table_core.c","net/netfilter/nf_flow_table_ip.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.19"},{"lessThan":"6.19","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.5","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.2","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.5","versionStartIncluding":"6.19","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2","versionStartIncluding":"6.19","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: flowtable: support IPIP tunnel with direct xmit\n\nThe combination of IPIP tunnel with direct xmit, eg. bridge device,\nbreaks because no dst_entry is provided to check the skb headroom and to\nset the iph->frag_off field. This leads to invalid dst usage and can\ntrigger a crash in the tunnel transmit path.\n\nFix this by moving dst_cache and dst_cookie out of the runtime union so\nthat they can be shared by neighbour, xfrm, and direct tunnel flows.\nFor FLOW_OFFLOAD_XMIT_DIRECT tuples carrying tunnel metadata, preserve\nroute state in these shared fields and release it through the common\ndst release path.\n\nSince dst_entry is now available to the three supported xmit modes and\ndst_release() already deals with NULL dst, remove the xmit type check\nin nft_flow_dst_release(). Moreover, skip the check if the dst entry\nis NULL in nf_flow_dst_check() which is now the case for the direct\nxmit case.\n\nBased on patch from Rein Wei <n05ec@lzu.edu.cn>."}],"metrics":[{"cvssV3_1":{"baseScore":9.8,"baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:N - The bug is hit in the netfilter flowtable ingress fast path when remotely sourced TCP/UDP packets matching an offloaded flow are received on flowtable-bound interfaces, not via netlink configuration APIs.\nAC:L - An attacker can reliably establish the offloaded flow by sending matching traffic and then repeatedly trigger the faulty IPIP direct-xmit tunnel push on subsequent packets without depending on uncontrollable timing or memory layout.\nPR:N - Exploitation requires only the ability to send network traffic through an already deployed IPIP-through-bridge flowtable offload path; no local account, authentication, or CAP_NET_ADMIN on the target is needed to trigger the crash.\nUI:N - No victim interaction is required beyond normal network traffic delivery; the attacker does not need the user to open files, mount filesystems, or perform any deliberate action.\nS:U - Impact is confined to kernel memory corruption and denial of service on the affected network namespace/host; it does not cross a VM, container, or IOMMU security boundary to compromise a separate authority.\nC:H - FLOW_OFFLOAD_XMIT_DIRECT stores MAC/ifindex data in a union aliasing dst_cache, so nf_flow_tunnel_ipip_push dereferences attacker-influenced bytes as a dst_entry/rtable, enabling uncontrolled kernel memory reads before the fault.\nI:H - The same invalid dst pointer drives skb_cow_head/headroom calculations and tunnel header writes in kernel transmit context, giving a plausible path to heap corruption and control-flow disruption beyond a simple NULL dereference.\nA:H - Invalid dst usage in the IPIP tunnel transmit path can cause kernel oops/panic or hard lockup when offloaded flows are exercised, fully denying availability of the affected system."}]}],"providerMetadata":{"dateUpdated":"2026-08-17T05:41:59.975Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/0880c4ed122d0cddc9f29a2b28f055d1f24f0fca"},{"url":"https://git.kernel.org/stable/c/fa7395c02d95e51bad2952325d2d6503bfbad437"}],"title":"netfilter: flowtable: support IPIP tunnel with direct xmit","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-72248","datePublished":"2026-08-15T05:54:36.535Z","dateReserved":"2026-08-09T03:40:39.914Z","dateUpdated":"2026-08-17T05:41:59.975Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-15 06:21:52","lastModifiedDate":"2026-08-17 06:18:26","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":3.9,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"72248","Ordinal":"1","Title":"netfilter: flowtable: support IPIP tunnel with direct xmit","CVE":"CVE-2026-72248","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"72248","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: flowtable: support IPIP tunnel with direct xmit\n\nThe combination of IPIP tunnel with direct xmit, eg. bridge device,\nbreaks because no dst_entry is provided to check the skb headroom and to\nset the iph->frag_off field. This leads to invalid dst usage and can\ntrigger a crash in the tunnel transmit path.\n\nFix this by moving dst_cache and dst_cookie out of the runtime union so\nthat they can be shared by neighbour, xfrm, and direct tunnel flows.\nFor FLOW_OFFLOAD_XMIT_DIRECT tuples carrying tunnel metadata, preserve\nroute state in these shared fields and release it through the common\ndst release path.\n\nSince dst_entry is now available to the three supported xmit modes and\ndst_release() already deals with NULL dst, remove the xmit type check\nin nft_flow_dst_release(). Moreover, skip the check if the dst entry\nis NULL in nf_flow_dst_check() which is now the case for the direct\nxmit case.\n\nBased on patch from Rein Wei <n05ec@lzu.edu.cn>.","Type":"Description","Title":"netfilter: flowtable: support IPIP tunnel with direct xmit"}]}}}