{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-98096", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:19:56.076Z", "datePublished": "2026-09-25T10:24:27.098Z", "dateUpdated": "2026-10-19T09:13:48.508Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T09:13:48.508Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: sr: restore network header before routing and forwarding\n\nipv6_srh_rcv() runs with skb->data at the Segment Routing Header (SRH)\nwhile skb_network_header() points at the IPv6 header.\n\nWhen segments_left > 0, ipv6_srh_rcv() previously restored the skb->data\nposition by pushing sizeof(struct ipv6hdr), assuming the SRH immediately\nfollowed the fixed IPv6 header. If another extension header (such as a\nHop-by-Hop options header) precedes the SRH, skb_network_offset()\nremained negative.\n\nThis led to two problems:\n1. During ip6_route_input(), fib6_rules_early_flow_dissect() invokes\n __skb_flow_dissect() which passes the negative skb_network_offset()\n to flow dissection, breaking BPF and C flow dissector logic.\n2. If forwarded via ip6_forward() or redirected via act_mirred, downstream\n handlers (like sch_fragment() or neighbour output) pass the negative\n offset as an unsigned length, triggering OOB memcpy or buffer overflows.\n\nFix this by pushing -skb_network_offset(skb) before routing, ensuring\nskb_network_offset(skb) is 0 for route lookup / flow dissection as well as\ndownstream forwarding. On the loopback path, pull skb_transport_offset(skb)\nto restore skb->data to the SRH before looping back." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H", "baseScore": 7.4, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - The bad input is a routed IPv6 packet sent by a remote host: a Hop-by-Hop header followed by an SRH with segments_left>0. ipv6_srh_rcv() processes it on receive, and its fixed skb_push(sizeof(struct ipv6hdr)) leaves skb_network_offset() negative before ip6_route_input() and dst_input() forward the packet.\nAC:H - ipv6_srh_rcv() drops the packet unless seg6_enabled, which defaults to 0, is set both in devconf_all and on the ingress interface. The out-of-bounds memcpy in sch_frag_prepare_frag() also needs the admin to have set up tc act_ct with an MRU plus act_mirred on the forwarding path. The remote attacker cannot set up either of these.\nPR:N - No authentication is needed to send the packet. seg6_hmac_validate_skb() accepts SRHs that carry no HMAC TLV when seg6_require_hmac is at its default of 0, so an unauthenticated sender reaches the segments_left>0 branch.\nUI:N - No victim action is needed. The router processes the attacker's SRH packet in softirq receive context as soon as it arrives.\nS:U - The corruption stays inside the router's own kernel (skb metadata, then the per-CPU sch_frag_data_storage and memory after it). No VM, IOMMU or sandbox boundary is crossed.\nC:N - With the negative offset, the flow dissector and the neighbour output path read or write inside the skb head, and the bytes sch_frag reads out of bounds go into per-CPU storage. I found no path that sends kernel memory back to the attacker.\nI:H - sch_frag_prepare_frag() takes the negative skb_network_offset() as unsigned hlen and runs memcpy(&data->l2_data, skb->data, hlen). That writes packet bytes the attacker supplied past the per-CPU sch_frag_data_storage buffer, an out-of-bounds kernel write.\nA:H - The roughly 4 GB memcpy in sch_frag_prepare_frag() will fault and crash the router. On other paths the negative offset breaks flow dissection and garbles forwarded packets. The attacker can repeat this with each crafted packet." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ipv6/exthdrs.c" ], "versions": [ { "version": "1ababeba4a21f3dba3da3523c670b207fb2feb62", "lessThan": "f463c4786cf27376de7dfc0833a12e924a98f698", "status": "affected", "versionType": "git" }, { "version": "1ababeba4a21f3dba3da3523c670b207fb2feb62", "lessThan": "8f44d4160bcdb3136a9145a4b9c7816382976925", "status": "affected", "versionType": "git" }, { "version": "1ababeba4a21f3dba3da3523c670b207fb2feb62", "lessThan": "9cfbe2c381ab6d00a08e7a5b6028865adfb4e1bc", "status": "affected", "versionType": "git" }, { "version": "1ababeba4a21f3dba3da3523c670b207fb2feb62", "lessThan": "af08f62b5a5a446d6134a92d86771d3d12e0e3da", "status": "affected", "versionType": "git" }, { "version": "1ababeba4a21f3dba3da3523c670b207fb2feb62", "lessThan": "ce4c8beedc19aceeab0e7bdc6f34394fb158c47c", "status": "affected", "versionType": "git" }, { "version": "1ababeba4a21f3dba3da3523c670b207fb2feb62", "lessThan": "97b21ef57dfabbff660a4672c9fef7edfb720f47", "status": "affected", "versionType": "git" }, { "version": "1ababeba4a21f3dba3da3523c670b207fb2feb62", "lessThan": "3ad7dca5e03bd64c65983a19734337512fd75491", "status": "affected", "versionType": "git" }, { "version": "1ababeba4a21f3dba3da3523c670b207fb2feb62", "lessThan": "975b5b067f525a1b1338c4a3bee1c46545801518", "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/ipv6/exthdrs.c" ], "versions": [ { "version": "4.10", "status": "affected" }, { "version": "0", "lessThan": "4.10", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.271", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.222", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.189", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.158", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.111", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.53", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.7", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "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": "4.10", "versionEndExcluding": "5.10.271" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.10", "versionEndExcluding": "5.15.222" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.10", "versionEndExcluding": "6.1.189" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.10", "versionEndExcluding": "6.6.158" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.10", "versionEndExcluding": "6.12.111" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.10", "versionEndExcluding": "6.18.53" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.10", "versionEndExcluding": "7.2.7" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.10", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/f463c4786cf27376de7dfc0833a12e924a98f698" }, { "url": "https://git.kernel.org/stable/c/8f44d4160bcdb3136a9145a4b9c7816382976925" }, { "url": "https://git.kernel.org/stable/c/9cfbe2c381ab6d00a08e7a5b6028865adfb4e1bc" }, { "url": "https://git.kernel.org/stable/c/af08f62b5a5a446d6134a92d86771d3d12e0e3da" }, { "url": "https://git.kernel.org/stable/c/ce4c8beedc19aceeab0e7bdc6f34394fb158c47c" }, { "url": "https://git.kernel.org/stable/c/97b21ef57dfabbff660a4672c9fef7edfb720f47" }, { "url": "https://git.kernel.org/stable/c/3ad7dca5e03bd64c65983a19734337512fd75491" }, { "url": "https://git.kernel.org/stable/c/975b5b067f525a1b1338c4a3bee1c46545801518" } ], "title": "ipv6: sr: restore network header before routing and forwarding", "x_generator": { "engine": "bippy-1.2.0" } } } }