CVE-2026-64132

Estado: AnalizadaCrítica (9.8)—

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

ipv6: ioam: refresh hdr pointer before ioam6_event()

Reported by Sashiko:

In ipv6_hop_ioam(), the hdr pointer is initialized to point into the skb's linear data buffer. Later, the code calls skb_ensure_writable(), which might reallocate the buffer:

If the skb is cloned or lacks sufficient linear headroom, skb_ensure_writable() will invoke pskb_expand_head(), which reallocates the skb's data buffer and frees the old one, invalidating pointers to it. While the code recalculates the trace pointer immediately after the call to skb_ensure_writable(), it fails to recalculate the hdr pointer.

Leer descripción completaMostrar menos

This patch fixes the above by recalculating the hdr pointer before passing hdr->opt_len to ioam6_event(), so that we avoid any UaF.

Detalles técnicos trazas, registros y código del informe original

	if (skb_ensure_writable(skb, optoff + 2 + hdr->opt_len))
		goto drop;

	/* Trace pointer may have changed */
	trace = (struct ioam6_trace_hdr *)(skb_network_header(skb)
					   + optoff + sizeof(*hdr));

	ioam6_fill_trace_data(skb, ns, trace, true);

	ioam6_event(IOAM6_EVENT_TRACE, dev_net(skb->dev),
		    GFP_ATOMIC, (void *)trace, hdr->opt_len - 2);

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Puntuación base: 9.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.67%
Percentil entre todas las CVEs puntuadas: 50
Fecha de la puntuación: 5/10/2026

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).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

ExplotaciónT1190 Exploit Public-Facing Applicationinitial access75 %

Vulnerabilidad de use-after-free (CWE-416) en kernel Linux explotable remotamente vía paquetes IPv6 malformados (AV:N, PR:N). La realocación de buffer causa ejecución de código arbitrario.

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Vulnerability Scanning Privileged Account Management Network Segmentation Limit Access to Resource Over Network Filter Network Traffic Application Isolation and Sandboxing

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

CWE-416

Referencias

JSON original (NVD)

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          "programFiles": [
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          "defaultStatus": "unaffected"
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          ],
          "programFiles": [
            "net/ipv6/exthdrs.c"
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          "defaultStatus": "affected"
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  "published": "2026-07-19T16:17:55.000",
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      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
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          "value": "CWE-416"
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  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: ioam: refresh hdr pointer before ioam6_event()\n\nReported by Sashiko:\n\nIn ipv6_hop_ioam(), the hdr pointer is initialized to point into the\nskb's linear data buffer. Later, the code calls skb_ensure_writable(),\nwhich might reallocate the buffer:\n\n\tif (skb_ensure_writable(skb, optoff + 2 + hdr->opt_len))\n\t\tgoto drop;\n\n\t/* Trace pointer may have changed */\n\ttrace = (struct ioam6_trace_hdr *)(skb_network_header(skb)\n\t\t\t\t\t   + optoff + sizeof(*hdr));\n\n\tioam6_fill_trace_data(skb, ns, trace, true);\n\n\tioam6_event(IOAM6_EVENT_TRACE, dev_net(skb->dev),\n\t\t    GFP_ATOMIC, (void *)trace, hdr->opt_len - 2);\n\nIf the skb is cloned or lacks sufficient linear headroom,\nskb_ensure_writable() will invoke pskb_expand_head(), which reallocates\nthe skb's data buffer and frees the old one, invalidating pointers to\nit. While the code recalculates the trace pointer immediately after the\ncall to skb_ensure_writable(), it fails to recalculate the hdr pointer.\n\nThis patch fixes the above by recalculating the hdr pointer before\npassing hdr->opt_len to ioam6_event(), so that we avoid any UaF."
    }
  ],
  "lastModified": "2026-08-13T15:10:12.260",
  "configurations": [
    {
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