CVE-2026-80615 (GCVE-0-2026-80615)

Vulnerability from cvelistv5 – Published: 2026-08-28 06:48 – Updated: 2026-08-29 06:21
VLAI
Title
net: dst_metadata: fix false-positive memcpy overflow in tun_dst_unclone
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.
Severity
8.2 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 69050f8d6d075dc01af7a5f2f550a8067510366f , < 7ce31739fe88a558370135db95bbeec1e7ddfc29 (git)
Affected: 69050f8d6d075dc01af7a5f2f550a8067510366f , < 4c6d43db2a4d2cef3921e885cf34798f790d34ea (git)
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Linux Linux Affected: 7.0
Unaffected: 0 , < 7.0 (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/net/dst_metadata.h"
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          "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."
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            "version": "3.1"
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          "scenarios": [
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              "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."
            }
          ]
        }
      ],
      "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"
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        {
          "url": "https://git.kernel.org/stable/c/4c6d43db2a4d2cef3921e885cf34798f790d34ea"
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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"
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-31T16:47:09+00:00",
      "cve": "CVE-2026-80615",
      "id": "CVE-2026-80615",
      "initial_release_date": "2026-08-28T00:00:00+00:00",
      "product_status:known_affected": "198",
      "product_status:known_not_affected": "76",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: net: dst_metadata: fix false-positive memcpy overflow in tun_dst_unclone",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80615.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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