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

Vulnerability from cvelistv5 – Published: 2026-07-19 15:40 – Updated: 2026-07-20 13:43
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
Linux Linux Affected: f655c78d6225f585ef60a9d93ffb79d507ff3ad3 , < 769723124b7c3b2bfea4cf68ad292698b87c8d01 (git)
Affected: f655c78d6225f585ef60a9d93ffb79d507ff3ad3 , < 24de676da63c1122d2c13b0d546238b66d1b4e62 (git)
Affected: f655c78d6225f585ef60a9d93ffb79d507ff3ad3 , < 5af905aa8e91ff8d94572a1e089558f21dcf24ed (git)
Affected: f655c78d6225f585ef60a9d93ffb79d507ff3ad3 , < e46e6bc97fb1f339730ff1ba74267fbf48e7a422 (git)
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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)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv6/exthdrs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "769723124b7c3b2bfea4cf68ad292698b87c8d01",
              "status": "affected",
              "version": "f655c78d6225f585ef60a9d93ffb79d507ff3ad3",
              "versionType": "git"
            },
            {
              "lessThan": "24de676da63c1122d2c13b0d546238b66d1b4e62",
              "status": "affected",
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              "versionType": "git"
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              "status": "affected",
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              "versionType": "git"
            },
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              "status": "affected",
              "version": "f655c78d6225f585ef60a9d93ffb79d507ff3ad3",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/ipv6/exthdrs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.9"
            },
            {
              "lessThan": "6.9",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.92",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.34",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.92",
                  "versionStartIncluding": "6.9",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.34",
                  "versionStartIncluding": "6.9",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0.11",
                  "versionStartIncluding": "6.9",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1",
                  "versionStartIncluding": "6.9",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "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\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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          }
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-20T13:43:38.348Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/769723124b7c3b2bfea4cf68ad292698b87c8d01"
        },
        {
          "url": "https://git.kernel.org/stable/c/24de676da63c1122d2c13b0d546238b66d1b4e62"
        },
        {
          "url": "https://git.kernel.org/stable/c/5af905aa8e91ff8d94572a1e089558f21dcf24ed"
        },
        {
          "url": "https://git.kernel.org/stable/c/e46e6bc97fb1f339730ff1ba74267fbf48e7a422"
        }
      ],
      "title": "ipv6: ioam: refresh hdr pointer before ioam6_event()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64132",
    "datePublished": "2026-07-19T15:40:27.590Z",
    "dateReserved": "2026-07-19T07:54:57.036Z",
    "dateUpdated": "2026-07-20T13:43:38.348Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-64132",
      "date": "2026-07-21",
      "epss": "0.00497",
      "percentile": "0.39407"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-64132\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-07-19T16:17:55.000\",\"lastModified\":\"2026-07-20T15:17:11.413\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"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\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.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"net/ipv6/exthdrs.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"f655c78d6225f585ef60a9d93ffb79d507ff3ad3\",\"lessThan\":\"769723124b7c3b2bfea4cf68ad292698b87c8d01\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"f655c78d6225f585ef60a9d93ffb79d507ff3ad3\",\"lessThan\":\"24de676da63c1122d2c13b0d546238b66d1b4e62\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"f655c78d6225f585ef60a9d93ffb79d507ff3ad3\",\"lessThan\":\"5af905aa8e91ff8d94572a1e089558f21dcf24ed\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"f655c78d6225f585ef60a9d93ffb79d507ff3ad3\",\"lessThan\":\"e46e6bc97fb1f339730ff1ba74267fbf48e7a422\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"net/ipv6/exthdrs.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.9\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.9\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.92\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.34\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.0.11\",\"lessThanOrEqual\":\"7.0.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":9.8,\"baseSeverity\":\"CRITICAL\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":5.9}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/24de676da63c1122d2c13b0d546238b66d1b4e62\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/5af905aa8e91ff8d94572a1e089558f21dcf24ed\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/769723124b7c3b2bfea4cf68ad292698b87c8d01\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/e46e6bc97fb1f339730ff1ba74267fbf48e7a422\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-07-20T15:27:32+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": "185",
      "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"
    }
  }
}



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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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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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