{"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":"2026-10-03T11:02:21.368Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-10-03T11:02:21.368Z"},"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-rc2","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-rc2"}]}]}],"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"}}}}