CVE-2026-64132 (GCVE-0-2026-64132)

Vulnerability from cvelistv5 – Published: 2026-07-19 15:40 – Updated: 2026-08-05 12:39
VLAI
Title
ipv6: ioam: refresh hdr pointer before ioam6_event()
Summary
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 (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); 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. This patch fixes the above by recalculating the hdr pointer before passing hdr->opt_len to ioam6_event(), so that we avoid any UaF.
Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: f655c78d6225f585ef60a9d93ffb79d507ff3ad3 , < 769723124b7c3b2bfea4cf68ad292698b87c8d01 (git)
Affected: f655c78d6225f585ef60a9d93ffb79d507ff3ad3 , < 24de676da63c1122d2c13b0d546238b66d1b4e62 (git)
Affected: f655c78d6225f585ef60a9d93ffb79d507ff3ad3 , < 5af905aa8e91ff8d94572a1e089558f21dcf24ed (git)
Affected: f655c78d6225f585ef60a9d93ffb79d507ff3ad3 , < e46e6bc97fb1f339730ff1ba74267fbf48e7a422 (git)
guessed Create a notification for this product.
Linux Linux Affected: 6.9
Unaffected: 0 , < 6.9 (semver)
Unaffected: 6.12.92 , ≤ 6.12.* (semver)
Unaffected: 6.18.34 , ≤ 6.18.* (semver)
Unaffected: 7.0.11 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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            "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\u0027s 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-\u003eopt_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-\u003edev),\n\t\t    GFP_ATOMIC, (void *)trace, hdr-\u003eopt_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\u0027s 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-\u003eopt_len to ioam6_event(), so that we avoid any UaF."
          }
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        "vulnStatus": "Analyzed",
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              {
                "lang": "en",
                "value": "CWE-416"
              }
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            "source": "nvd@nist.gov",
            "type": "Primary"
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    },
    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-09-14T18:09:29+00:00",
      "cve": "CVE-2026-64132",
      "id": "CVE-2026-64132",
      "initial_release_date": "2026-07-19T00:00:00+00:00",
      "product_status:known_affected": "76",
      "product_status:known_not_affected": "184",
      "product_status:under_investigation": "14",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ipv6: ioam: refresh hdr pointer before ioam6_event()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64132.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-15T01:54:52Z",
      "cve": "CVE-2026-64132",
      "id": "CVE-2026-64132",
      "initial_release_date": "2026-07-21T12:59:07Z",
      "product_status:known_affected": "29",
      "product_status:known_not_affected": "345",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-64132",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-64132.json",
      "version": "6"
    }
  }
}



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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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