CVE-2026-80615 (GCVE-0-2026-80615)
Vulnerability from cvelistv5
Published
2026-08-28 06:48
Modified
2026-08-29 06:21
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
net: dst_metadata: fix false-positive memcpy overflow in tun_dst_unclone
kmalloc_flex() in metadata_dst_alloc() sets __counted_by for the
structure to the options_len, which is then initialized to zero.
Later, we're initializing the structure by copying the tunnel info
together with the options, and this triggers a warning for a potential
memcpy overflow, since the compiler estimates that the options can't
fit into the structure, even though the memory for them is actually
allocated.
memcpy: detected buffer overflow: 104 byte write of buffer size 96
WARNING: CPU: X PID: Y at lib/string_helpers.c:1036 __fortify_report
skb_tunnel_info_unclone+0x179/0x190
geneve_xmit+0x7fe/0xe00
The issue is triggered when built with clang and source fortification.
Fix that by doing the copy in two stages: first - the main data with
the options_len, then the options. This way the correct length should
be known at the time of the copy.
It would be better if the options_len never changed after allocation,
but the allocation code is a little separate from the initialization
and it would be awkward and potentially dangerous to return a struct
with options_len set to a non-zero value from the metadata_dst_alloc().
Another option would be to use ip_tunnel_info_opts_set(), but it is
doing too many unnecessary operations for the use case here.
References
Impacted products
{
"containers": {
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"affected": [
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"product": "Linux",
"programFiles": [
"include/net/dst_metadata.h"
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"vendor": "Linux",
"versions": [
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"vendor": "Linux",
"versions": [
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"version": "7.0"
},
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"status": "unaffected",
"version": "0",
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"version": "7.1.5",
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{
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"status": "unaffected",
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"descriptions": [
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"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: dst_metadata: fix false-positive memcpy overflow in tun_dst_unclone\n\nkmalloc_flex() in metadata_dst_alloc() sets __counted_by for the\nstructure to the options_len, which is then initialized to zero.\nLater, we\u0027re initializing the structure by copying the tunnel info\ntogether with the options, and this triggers a warning for a potential\nmemcpy overflow, since the compiler estimates that the options can\u0027t\nfit into the structure, even though the memory for them is actually\nallocated.\n\n memcpy: detected buffer overflow: 104 byte write of buffer size 96\n WARNING: CPU: X PID: Y at lib/string_helpers.c:1036 __fortify_report\n skb_tunnel_info_unclone+0x179/0x190\n geneve_xmit+0x7fe/0xe00\n\nThe issue is triggered when built with clang and source fortification.\n\nFix that by doing the copy in two stages: first - the main data with\nthe options_len, then the options. This way the correct length should\nbe known at the time of the copy.\n\nIt would be better if the options_len never changed after allocation,\nbut the allocation code is a little separate from the initialization\nand it would be awkward and potentially dangerous to return a struct\nwith options_len set to a non-zero value from the metadata_dst_alloc().\n\nAnother option would be to use ip_tunnel_info_opts_set(), but it is\ndoing too many unnecessary operations for the use case here."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 8.2,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - The bug is reached from geneve_xmit/vxlan_xmit and OVS dev_fill_metadata_dst during overlay packet transmit; remote peers can inject Geneve/VXLAN UDP traffic with tunnel options that later traverse skb_tunnel_info_unclone() on cloud, Kubernetes, and OpenStack/OVN nodes.\nAC:L - On kernels built with CONFIG_FORTIFY_SOURCE and clang, a remote attacker can deterministically trigger the fortified memcpy check by sending Geneve/VXLAN packets carrying non-zero tunnel options that provoke PMTU handling or OVS egress-metadata cloning; no races or victim-specific memory layout are required.\nPR:N - Exploitation requires only that the target host already runs Geneve/VXLAN/OVS overlay netdevs, which is routine in data centers; remote overlay peers and unauthenticated senders whose packets are forwarded through these tunnels need no elevated privileges on the target system.\nUI:N - The fortify warning is triggered automatically during kernel packet transmit or OVS metadata handling with no action required from a local user or administrator beyond normal network operation on an overlay-enabled host.\nS:U - Impact is a kernel fortify WARN/BUG in the host networking stack during tunnel metadata cloning; it does not cross VM, container, or IOMMU security boundaries into another authority domain.\nC:L - No actual out-of-bounds read occurs because fortify halts the memcpy before any real overflow, but __fortify_report() emits a kernel warning and call trace that can disclose limited kernel text/layout information useful for further exploitation.\nI:N - This is a fortify false positive: metadata_dst_alloc() correctly sizes the destination via kmalloc_flex() and fortify aborts before the memcpy executes; there is no memory corruption, arbitrary write, or code-execution primitive.\nA:H - Triggering the fortify check calls __fortify_panic(), which issues WARN then BUG(), causing a kernel oops/panic and immediate denial of service on overlay hosts processing malicious Geneve/VXLAN tunnel-metadata traffic."
}
]
}
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"providerMetadata": {
"dateUpdated": "2026-08-29T06:21:24.054Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
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"references": [
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"url": "https://git.kernel.org/stable/c/7ce31739fe88a558370135db95bbeec1e7ddfc29"
},
{
"url": "https://git.kernel.org/stable/c/4c6d43db2a4d2cef3921e885cf34798f790d34ea"
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"title": "net: dst_metadata: fix false-positive memcpy overflow in tun_dst_unclone",
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"cveMetadata": {
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"assignerShortName": "Linux",
"cveId": "CVE-2026-80615",
"datePublished": "2026-08-28T06:48:36.315Z",
"dateReserved": "2026-08-26T14:34:25.774Z",
"dateUpdated": "2026-08-29T06:21:24.054Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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