264 lines
15 KiB
JSON
264 lines
15 KiB
JSON
{
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"dataType": "CVE_RECORD",
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"dataVersion": "5.2",
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"cveMetadata": {
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"cveId": "CVE-2026-80976",
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"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"state": "PUBLISHED",
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"assignerShortName": "Linux",
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"dateReserved": "2026-08-26T14:34:25.810Z",
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"datePublished": "2026-09-11T19:42:38.215Z",
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"dateUpdated": "2026-10-19T08:46:00.756Z"
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},
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"containers": {
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"cna": {
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"providerMetadata": {
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"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"shortName": "Linux",
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"dateUpdated": "2026-10-19T08:46:00.756Z"
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},
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"descriptions": [
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{
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"lang": "en",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nseg6: reset IP6CB after IPv6 decapsulation\n\ndecap_and_validate() pulls the outer SRv6 headers and makes the inner\npacket the skb network header. The IPv6 control block still contains\nvalues collected while parsing the outer packet, including nhoff and\nextension-header flags.\n\nEnd.DX6 and End.DT6 route the inner IPv6 packet directly to the IPv6\ninput path. An unprivileged user can reach End.DT6 from a user and net\nnamespace by installing a local SID and injecting an outer packet with\nHop-by-Hop and Destination Options headers followed by an SRH and a\nminimal inner IPv6 packet.\n\nThe outer extension headers leave a large nhoff in IP6CB. After\ndecapsulation, ip6_protocol_deliver_rcu() uses that stale offset on the\ninner packet and reads beyond the skb head. KASAN reports:\n\n BUG: KASAN: slab-out-of-bounds in ip6_protocol_deliver_rcu\n ip6_protocol_deliver_rcu+0x1118/0x1450\n ip6_input_finish+0x11b/0x240\n seg6_local_input_core+0xed/0x2e0\n lwtunnel_input+0x1e9/0x4e0\n ipv6_rthdr_rcv+0x525f/0x6c50\n ip6_protocol_deliver_rcu+0xcb7/0x1450\n\nBefore clearing IP6CB for an inner IPv6 packet, save its incoming\ninterface index and L3 slave state. Restore both after the clear and set\nnhoff to the inner IPv6 base-header nexthdr field.\n\nUse IP6CB(skb)->iif rather than skb->skb_iif because VRF processing can\nreplace skb_iif with the L3 master while IP6CB keeps the receiving\ninterface. Preserve IP6SKB_L3SLAVE for the same reason."
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}
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],
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"metrics": [
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{
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"cvssV3_1": {
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"version": "3.1",
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"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
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"baseScore": 9.8,
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"baseSeverity": "CRITICAL"
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},
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"scenarios": [
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{
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"lang": "en",
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"value": "AV:N - End.DT6/End.DX6 run on the IPv6 receive path (ipv6_rthdr_rcv/lwtunnel_input/seg6_local_input_core) when a packet targets a configured local SID; a remote attacker who can route IPv6/SRv6 traffic to that SID on an SRv6 PE, VPN edge, or similar node triggers decap without local access.\nAC:L - The attacker fully controls the outer Hop-by-Hop and Destination Options chain that inflates IP6CB nhoff and the inner packet length, so one crafted packet deterministically makes ip6_protocol_deliver_rcu() index past the skb head with no race or uncontrolled layout.\nPR:N - SID processing runs in receive softirq with no authentication; a configured End.DT6/End.DX6 SID is an environmental precondition, not a credential the network attacker must hold (the same path is also reachable by an unprivileged userns user installing a SID).\nUI:N - Exploitation requires only sending crafted IPv6 packets to the SID; no victim user or administrator action is needed beyond the pre-existing SRv6 configuration.\nS:U - The stale-nhoff out-of-bounds access affects kernel memory on the receiving host only; it does not cross a VM, IOMMU, or sandbox security boundary.\nC:H - After decap, ip6_protocol_deliver_rcu() does skb_network_header(skb)[nhoff] using a stale outer nhoff the attacker can push thousands of bytes past the inner skb, which is an out-of-bounds kernel read; the leaked byte is then used as nexthdr, exposing further slab contents via dispatch side effects.\nI:H - Stale nhoff selects the inet6 protocol handler, type-confusing the inner packet into an attacker-influenced parser; IPv6 fragment reassembly also writes skb_network_header(skb)[nhoff], so the same attacker-controlled offset becomes an out-of-bounds write when the inner flow is fragmented.\nA:H - KASAN reports slab-out-of-bounds in ip6_protocol_deliver_rcu() on this path; in production a large nhoff lands on unmapped memory and oopses/panics the kernel, and the packet can be repeated at line rate."
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}
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]
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}
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],
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"affected": [
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "unaffected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"net/ipv6/seg6_local.c"
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],
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"versions": [
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{
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"version": "d7a669dd2f8ba07a17423f4ad586dfc0379882f7",
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"lessThan": "d1f0d353358987ca87f21d8956e2d2854951130d",
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"status": "affected",
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"versionType": "git"
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},
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"lessThan": "a0e2b0a3718f0cf9fb0ee41710b4a6348a7315c8",
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"status": "affected",
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"status": "affected",
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},
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{
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"lessThan": "2b154e96fcb3f01fd42765c64e0a56820fbc16eb",
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"status": "affected",
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},
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{
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"version": "d7a669dd2f8ba07a17423f4ad586dfc0379882f7",
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"lessThan": "cfa186a0857a0f831dfca67b16bbc40ecfdf3280",
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"status": "affected",
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{
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"version": "d7a669dd2f8ba07a17423f4ad586dfc0379882f7",
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"lessThan": "c73fb911e02b9a766c950bc9707f3e3a96ffd702",
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"status": "affected",
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},
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{
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"version": "d7a669dd2f8ba07a17423f4ad586dfc0379882f7",
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"lessThan": "f967455fb2a5a2079b9eb5823e9ccf359174bf9f",
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"status": "affected",
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}
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]
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},
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "affected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"net/ipv6/seg6_local.c"
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],
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"versions": [
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{
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"version": "4.14",
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"status": "affected"
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},
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{
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"version": "0",
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"lessThan": "4.14",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "5.10.270",
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"lessThanOrEqual": "5.10.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "5.15.221",
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"lessThanOrEqual": "5.15.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.1.188",
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"lessThanOrEqual": "6.1.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.6.157",
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"lessThanOrEqual": "6.6.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.12.109",
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"lessThanOrEqual": "6.12.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.18.50",
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"lessThanOrEqual": "6.18.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "7.2.4",
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"lessThanOrEqual": "7.2.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "7.3",
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"lessThanOrEqual": "*",
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"status": "unaffected",
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"versionType": "original_commit_for_fix"
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}
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]
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}
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],
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"cpeApplicability": [
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"nodes": [
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"operator": "OR",
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"negate": false,
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"cpeMatch": [
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"references": [
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{
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"url": "https://git.kernel.org/stable/c/d1f0d353358987ca87f21d8956e2d2854951130d"
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},
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{
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"url": "https://git.kernel.org/stable/c/a0e2b0a3718f0cf9fb0ee41710b4a6348a7315c8"
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},
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{
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"url": "https://git.kernel.org/stable/c/9ae92198c24d7dacd4070e2f34f6e1ed3a63061c"
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},
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{
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"url": "https://git.kernel.org/stable/c/96c74420ac92930a7e0f21770818544eee4a93d7"
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},
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{
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"url": "https://git.kernel.org/stable/c/2b154e96fcb3f01fd42765c64e0a56820fbc16eb"
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},
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{
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"url": "https://git.kernel.org/stable/c/cfa186a0857a0f831dfca67b16bbc40ecfdf3280"
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},
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{
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"url": "https://git.kernel.org/stable/c/c73fb911e02b9a766c950bc9707f3e3a96ffd702"
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},
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{
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"url": "https://git.kernel.org/stable/c/f967455fb2a5a2079b9eb5823e9ccf359174bf9f"
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}
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],
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"title": "seg6: reset IP6CB after IPv6 decapsulation",
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"x_generator": {
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"engine": "bippy-1.2.0"
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}
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}
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}
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} |