CVE-2026-97612
📛 CVE Title
net: mpls: clear inner_protocol when the last label is popped
Description
In the Linux kernel, the following vulnerability has been resolved: net: mpls: clear inner_protocol when the last label is popped skb_mpls_push() records the pre-encapsulation network header once, gated on !skb->inner_protocol. skb_mpls_pop() never clears that record, so it outlives the encapsulation it describes. Open vSwitch can then re-push MPLS onto a packet whose inner_network_header still points at the older, deeper offset: push a label, pop every label, recirculate (ovs_flow_key_update() re-derives key->eth.type and resets network_header, but leaves inner_*), then push again. ovs_fragment() trusts the record: skb->network_header = skb->inner_network_header; so skb_network_offset() goes negative. The bound check is signed: if (skb_network_offset(skb) > MAX_L2_LEN) a negative offset passes it, and prepare_frag() widens the value: unsigned int hlen = skb_network_offset(skb); memcpy(&data->l2_data, skb->data, hlen); which is a ~4GiB memcpy out of a 30-byte per-CPU buffer. Reproduced on v7.3-rc1. RDX is the truncated length, (unsigned int)(-8): BUG: unable to handle page fault for address: ffffe8ffffc16000 #PF: supervisor write access in kernel mode Oops: 0002 [#1] SMP KASAN NOPTI RIP: 0010:memcpy+0x8/0x20 RDX: 00000000fffffff8 RSI: ffff888105d732db RDI: ffffe8ffffc16000 prepare_frag+0x3df/0x4e0 ovs_fragment+0x589/0x7e0 do_output+0x4ce/0x5e0 do_execute_actions+0x55d2/0x7b30 ovs_execute_actions+0xea/0x450 Same root-cause shape as commit 975b5b067f52 ("ipv6: sr: restore network header before routing and forwarding"): a stale network header offset reaching a consumer that widens it. Here it originates in the MPLS push/pop path. Clear inner_protocol once the packet is no longer MPLS, so a later push re-records the current header. net/sched/act_mpls.c is the only other skb_mpls_pop() caller and gets the same fix; sch_frag.c saves and restores inner_protocol around fragmentation in the same way OVS does.
Overview
- State
- PUBLISHED
- Assigner (CNA)
- Linux
- CVSS severity
- HIGH
- CVSS score
- 7.8 / 10
- CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H- Effective score
- 7.8 / 10 HIGH source: CNA overview
- CWE(s)
- —
- Reserved
- 2026-09-24
- Published
- 2026-09-25 10:22 UTC
- Last updated
- 2026-09-25 14:41 UTC
- Source
- https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/97xxx/CVE-2026-97612.json
- Linked Threat
- CVE-2026-97612 — net: mpls: clear inner_protocol when the last label is popped
NVD triage scoring NVD CVE 2.0
Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.
- NVD published
- 2026-09-25 11:17:15 UTC
- NVD last modified
- 2026-09-25 15:18:01 UTC
- NVD CVSS v3.1
- 7.8 / 10 HIGH source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
- NVD CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H- Exploitability subscore
- 1.8 / 10
- Impact subscore
- 5.9 / 10
NVD / KEV / EPSS data refreshed 2026-09-26 04:28 UTC. Re-run the 🛰 Backfill from NVD button above to refresh.
Affected products (2)
| Vendor | Product | Versions | Platforms |
|---|---|---|---|
| Linux | Linux |
48d2ab609b6bbecb7698487c8579bc40de9d6dfa (affected),
48d2ab609b6bbecb7698487c8579bc40de9d6dfa (affected),
48d2ab609b6bbecb7698487c8579bc40de9d6dfa (affected),
48d2ab609b6bbecb7698487c8579bc40de9d6dfa (affected)
|
— |
| Linux | Linux |
4.9 (affected),
0 (unaffected),
6.12.111 (unaffected),
6.18.53 (unaffected),
7.2.7 (unaffected),
7.3-rc3 (unaffected)
|
— |
Vendor references (4)
References embedded in the original CVE record by the assigning CNA.
Web references (0)
DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.
No web references attached yet.
NVD-tagged references (4)
Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.
- https://git.kernel.org/stable/c/011e17b5cae19b9f6a150923275e41c278de64f0 416baaa9-dc9f-4396-8d5f-8c081fb06d67
- https://git.kernel.org/stable/c/78a86d75a70e1e227711c72865c59b1422d0a5ae 416baaa9-dc9f-4396-8d5f-8c081fb06d67
- https://git.kernel.org/stable/c/b39120523475d6b436be7f6cb27d48064148a327 416baaa9-dc9f-4396-8d5f-8c081fb06d67
- https://git.kernel.org/stable/c/da8c3a7f5d3137fec4ff60a6248f5f6d66b6a63e 416baaa9-dc9f-4396-8d5f-8c081fb06d67
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Raw JSON
The full cvelistV5 record. Download as CVE-2026-97612.json.
{
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"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "4.9"
},
{
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"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.111",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "6.18.53",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.2.*",
"status": "unaffected",
"version": "7.2.7",
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},
{
"lessThanOrEqual": "*",
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"versionType": "original_commit_for_fix"
}
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"cpeApplicability": [
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"nodes": [
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"versionEndExcluding": "6.12.111",
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{
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},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: mpls: clear inner_protocol when the last label is popped\n\nskb_mpls_push() records the pre-encapsulation network header once, gated\non !skb->inner_protocol. skb_mpls_pop() never clears that record, so it\noutlives the encapsulation it describes.\n\nOpen vSwitch can then re-push MPLS onto a packet whose\ninner_network_header still points at the older, deeper offset: push a\nlabel, pop every label, recirculate (ovs_flow_key_update() re-derives\nkey->eth.type and resets network_header, but leaves inner_*), then push\nagain. ovs_fragment() trusts the record:\n\n\tskb->network_header = skb->inner_network_header;\n\nso skb_network_offset() goes negative. The bound check is signed:\n\n\tif (skb_network_offset(skb) > MAX_L2_LEN)\n\na negative offset passes it, and prepare_frag() widens the value:\n\n\tunsigned int hlen = skb_network_offset(skb);\n\tmemcpy(&data->l2_data, skb->data, hlen);\n\nwhich is a ~4GiB memcpy out of a 30-byte per-CPU buffer.\n\nReproduced on v7.3-rc1. RDX is the truncated length, (unsigned int)(-8):\n\n BUG: unable to handle page fault for address: ffffe8ffffc16000\n #PF: supervisor write access in kernel mode\n Oops: 0002 [#1] SMP KASAN NOPTI\n RIP: 0010:memcpy+0x8/0x20\n RDX: 00000000fffffff8 RSI: ffff888105d732db RDI: ffffe8ffffc16000\n prepare_frag+0x3df/0x4e0\n ovs_fragment+0x589/0x7e0\n do_output+0x4ce/0x5e0\n do_execute_actions+0x55d2/0x7b30\n ovs_execute_actions+0xea/0x450\n\nSame root-cause shape as commit 975b5b067f52 (\"ipv6: sr: restore network\nheader before routing and forwarding\"): a stale network header offset\nreaching a consumer that widens it. Here it originates in the MPLS\npush/pop path.\n\nClear inner_protocol once the packet is no longer MPLS, so a later push\nre-records the current header. net/sched/act_mpls.c is the only other\nskb_mpls_pop() caller and gets the same fix; sch_frag.c saves and\nrestores inner_protocol around fragmentation in the same way OVS does."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - The stale inner_network_header comes from OVS flow actions (push_mpls, pop_mpls, recirc, push_mpls) that the attacker installs over the ovs_flow/ovs_packet generic netlink families. No field of a received packet causes the bad offset, so the vector is local netlink rather than the wire.\nAC:L - The attacker chooses the flow action sequence and the oversized packet that sends do_output into ovs_fragment(). skb_mpls_pop() then deterministically leaves inner_protocol set, and the negative offset always passes the signed MAX_L2_LEN check, so nothing depends on timing or outside state.\nPR:L - The OVS datapath, vport, flow and packet genl operations use GENL_UNS_ADMIN_PERM with netnsok=true. That means CAP_NET_ADMIN inside an unprivileged user and network namespace (unshare -Urn) is enough to create a datapath, install the flows and execute packets.\nUI:N - No victim action is needed. The attacker installs the flows and injects or sends the packet themselves inside their own namespace.\nS:U - The overflow corrupts memory of the same kernel that performs the check. This is ordinary in-kernel memory corruption and crosses no hypervisor or IOMMU boundary.\nC:H - prepare_frag() turns a negative skb_network_offset() into an unsigned hlen of about 4 GiB and memcpy()s attacker packet bytes past the 30-byte per-CPU ovs_frag_data.l2_data. The write covers exec_level, owner, bh_lock and the per-CPU data that follows, and memory corruption of this kind can be leveraged for information disclosure.\nI:H - This is an out-of-bounds write of attacker-controlled skb data into the per-CPU ovs_pcpu_storage and the per-CPU memory after it, including a task_struct pointer (owner) and lock state. The corruption stays in place if the oops happens in process context (OVS_PACKET_CMD_EXECUTE).\nA:H - The runaway memcpy in prepare_frag() always runs until it hits an unmapped per-CPU page and oopses, as the fix's reproducer shows (write fault in memcpy from prepare_frag/ovs_fragment). The attacker can repeat this at will."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-09-25T14:41:34.217Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/011e17b5cae19b9f6a150923275e41c278de64f0"
},
{
"url": "https://git.kernel.org/stable/c/da8c3a7f5d3137fec4ff60a6248f5f6d66b6a63e"
},
{
"url": "https://git.kernel.org/stable/c/b39120523475d6b436be7f6cb27d48064148a327"
},
{
"url": "https://git.kernel.org/stable/c/78a86d75a70e1e227711c72865c59b1422d0a5ae"
}
],
"title": "net: mpls: clear inner_protocol when the last label is popped",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-97612",
"datePublished": "2026-09-25T10:22:21.423Z",
"dateReserved": "2026-09-24T16:01:01.158Z",
"dateUpdated": "2026-09-25T14:41:34.217Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
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