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CVE-2026-31517

Estado: AnalizadaMedia (5.5)—

In the Linux kernel, the following vulnerability has been resolved:

xfrm: iptfs: fix skb_put() panic on non-linear skb during reassembly

In iptfs_reassem_cont(), IP-TFS attempts to append data to the new inner packet 'newskb' that is being reassembled. First a zero-copy approach is tried if it succeeds then newskb becomes non-linear.

When a subsequent fragment in the same datagram does not meet the fast-path conditions, a memory copy is performed. It calls skb_put() to append the data and as newskb is non-linear it triggers SKB_LINEAR_ASSERT check.

Fix this by checking if the skb is non-linear. If it is, linearize it by calling skb_linearize().

Leer descripción completaMostrar menos

As the initial allocation of newskb originally reserved enough tailroom for the entire reassembled packet we do not need to check if we have enough tailroom or extend it.

Detalles técnicos trazas, registros y código del informe original
 Oops: invalid opcode: 0000 [#1] SMP NOPTI
 [...]
 RIP: 0010:skb_put+0x3c/0x40
 [...]
 Call Trace:
  <IRQ>
  iptfs_reassem_cont+0x1ab/0x5e0 [xfrm_iptfs]
  iptfs_input_ordered+0x2af/0x380 [xfrm_iptfs]
  iptfs_input+0x122/0x3e0 [xfrm_iptfs]
  xfrm_input+0x91e/0x1a50
  xfrm4_esp_rcv+0x3a/0x110
  ip_protocol_deliver_rcu+0x1d7/0x1f0
  ip_local_deliver_finish+0xbe/0x1e0
  __netif_receive_skb_core.constprop.0+0xb56/0x1120
  __netif_receive_skb_list_core+0x133/0x2b0
  netif_receive_skb_list_internal+0x1ff/0x3f0
  napi_complete_done+0x81/0x220
  virtnet_poll+0x9d6/0x116e [virtio_net]
  __napi_poll.constprop.0+0x2b/0x270
  net_rx_action+0x162/0x360
  handle_softirqs+0xdc/0x510
  __irq_exit_rcu+0xe7/0x110
  irq_exit_rcu+0xe/0x20
  common_interrupt+0x85/0xa0
  </IRQ>
  <TASK>

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

Referencias

JSON original (NVD)

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  "id": "CVE-2026-31517",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
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        "type": "Primary",
        "source": "nvd@nist.gov",
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          "version": "3.1",
          "baseScore": 5.5,
          "attackVector": "LOCAL",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "NONE"
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          "programFiles": [
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          "defaultStatus": "affected"
        }
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  "published": "2026-04-22T14:16:51.273",
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-401"
        }
      ]
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  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: iptfs: fix skb_put() panic on non-linear skb during reassembly\n\nIn iptfs_reassem_cont(), IP-TFS attempts to append data to the new inner\npacket 'newskb' that is being reassembled. First a zero-copy approach is\ntried if it succeeds then newskb becomes non-linear.\n\nWhen a subsequent fragment in the same datagram does not meet the\nfast-path conditions, a memory copy is performed. It calls skb_put() to\nappend the data and as newskb is non-linear it triggers\nSKB_LINEAR_ASSERT check.\n\n Oops: invalid opcode: 0000 [#1] SMP NOPTI\n [...]\n RIP: 0010:skb_put+0x3c/0x40\n [...]\n Call Trace:\n  <IRQ>\n  iptfs_reassem_cont+0x1ab/0x5e0 [xfrm_iptfs]\n  iptfs_input_ordered+0x2af/0x380 [xfrm_iptfs]\n  iptfs_input+0x122/0x3e0 [xfrm_iptfs]\n  xfrm_input+0x91e/0x1a50\n  xfrm4_esp_rcv+0x3a/0x110\n  ip_protocol_deliver_rcu+0x1d7/0x1f0\n  ip_local_deliver_finish+0xbe/0x1e0\n  __netif_receive_skb_core.constprop.0+0xb56/0x1120\n  __netif_receive_skb_list_core+0x133/0x2b0\n  netif_receive_skb_list_internal+0x1ff/0x3f0\n  napi_complete_done+0x81/0x220\n  virtnet_poll+0x9d6/0x116e [virtio_net]\n  __napi_poll.constprop.0+0x2b/0x270\n  net_rx_action+0x162/0x360\n  handle_softirqs+0xdc/0x510\n  __irq_exit_rcu+0xe7/0x110\n  irq_exit_rcu+0xe/0x20\n  common_interrupt+0x85/0xa0\n  </IRQ>\n  <TASK>\n\nFix this by checking if the skb is non-linear. If it is, linearize it by\ncalling skb_linearize(). As the initial allocation of newskb originally\nreserved enough tailroom for the entire reassembled packet we do not\nneed to check if we have enough tailroom or extend it."
    }
  ],
  "lastModified": "2026-06-17T10:33:53.873",
  "configurations": [
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