Vulnerability-Lookup

CVE-2026-98368 (GCVE-0-2026-98368)

Vulnerability from cvelistv5 – Published: 2026-10-06 08:46 – Updated: 2026-10-06 08:46

Title

esp: downgrade zerocopy managed frags before mutating skb frags

Summary

In the Linux kernel, the following vulnerability has been resolved: esp: downgrade zerocopy managed frags before mutating skb frags On the out-of-place output path (esp->inplace == false) ESP rewrites the skb frag array: esp_output_head() appends a trailer frag and esp_output_tail() replaces the frags with a destination page, both referenced with get_page(). When the skb carries zerocopy managed frags (SKBFL_MANAGED_FRAG_REFS) the payload frags are owned by the ubuf and must not be referenced or unreferenced individually, but ESP mutates the frag array without ever downgrading the skb. This breaks the managed-frag invariant two ways: - esp_ssg_unref() walks the source scatterlist and drops a page reference for every frag, including the ubuf-owned payload frags, pushing their refcount below the GUP pin bias while the pages are still pinned, i.e. a use-after-free of the zerocopy pages; - esp_output_tail() installs its destination page as frag 0 with get_page() but leaves SKBFL_MANAGED_FRAG_REFS set, so skb_release_data() takes the skip_unref branch and never drops that reference, leaking the x->xfrag page at packet rate. Fix this the way every other frag-mutating site does (__ip_append_data(), __ip6_append_data(), tcp_sendmsg_locked()) and call skb_zcopy_downgrade_managed() before ESP touches the frag array: it takes a real reference on each existing frag and clears SKBFL_MANAGED_FRAG_REFS, so the per-frag unref in esp_ssg_unref() and the frag release in skb_release_data() are both balanced and no mixed-ownership frag array is left behind.

Severity

No CVSS data available.

Assigner

Linux mitre root Scorecard

References

6 references

URL	Tags
https://git.kernel.org/stable/c/2359264f377cdbdef…
https://git.kernel.org/stable/c/69a768c12398cada8…
https://git.kernel.org/stable/c/6508304ac2c8cdafc…
https://git.kernel.org/stable/c/6cab554f2c0f28773…
https://git.kernel.org/stable/c/0d0845ee61c5df47c…
https://git.kernel.org/stable/c/f89416eb3db151170…

Impacted products

2 products

Vendor	Product	Version	CPE status
Linux	Linux	Affected: 753f1ca4e1e50248a1b760c9774d6d6b354562cc , < 2359264f377cdbdef2d95868cc8fb572949e48d3 (git) Affected: 753f1ca4e1e50248a1b760c9774d6d6b354562cc , < 69a768c12398cada8528080332c822623fa7064d (git) Affected: 753f1ca4e1e50248a1b760c9774d6d6b354562cc , < 6508304ac2c8cdafca2f4ab915df8c707893e134 (git) Affected: 753f1ca4e1e50248a1b760c9774d6d6b354562cc , < 6cab554f2c0f28773f712ed3a5479103f42ce844 (git) Affected: 753f1ca4e1e50248a1b760c9774d6d6b354562cc , < 0d0845ee61c5df47cc68bc446501f48f71e8dcc6 (git) Affected: 753f1ca4e1e50248a1b760c9774d6d6b354562cc , < f89416eb3db151170a6f3c6dfc5239d26cdce4d2 (git)	guessed
Linux	Linux	Affected: 6.0 Unaffected: 0 , < 6.0 (semver) Unaffected: 6.1.189 , ≤ 6.1.* (semver) Unaffected: 6.6.158 , ≤ 6.6.* (semver) Unaffected: 6.12.112 , ≤ 6.12.* (semver) Unaffected: 6.18.54 , ≤ 6.18.* (semver) Unaffected: 7.2.8 , ≤ 7.2.* (semver) Unaffected: 7.3-rc4 , ≤ * (original_commit_for_fix)	guessed

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv4/esp4.c",
            "net/ipv6/esp6.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "2359264f377cdbdef2d95868cc8fb572949e48d3",
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              "versionType": "git"
            },
            {
              "lessThan": "69a768c12398cada8528080332c822623fa7064d",
              "status": "affected",
              "version": "753f1ca4e1e50248a1b760c9774d6d6b354562cc",
              "versionType": "git"
            },
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              "versionType": "git"
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              "versionType": "git"
            },
            {
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              "versionType": "git"
            },
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              "status": "affected",
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              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/ipv4/esp4.c",
            "net/ipv6/esp6.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.0"
            },
            {
              "lessThan": "6.0",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.189",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.158",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.112",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.54",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc4",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.189",
                  "versionStartIncluding": "6.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.158",
                  "versionStartIncluding": "6.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.112",
                  "versionStartIncluding": "6.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.54",
                  "versionStartIncluding": "6.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.8",
                  "versionStartIncluding": "6.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc4",
                  "versionStartIncluding": "6.0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nesp: downgrade zerocopy managed frags before mutating skb frags\n\nOn the out-of-place output path (esp-\u003einplace == false) ESP rewrites the\nskb frag array: esp_output_head() appends a trailer frag and\nesp_output_tail() replaces the frags with a destination page, both\nreferenced with get_page().\n\nWhen the skb carries zerocopy managed frags (SKBFL_MANAGED_FRAG_REFS) the\npayload frags are owned by the ubuf and must not be referenced or\nunreferenced individually, but ESP mutates the frag array without ever\ndowngrading the skb.  This breaks the managed-frag invariant two ways:\n\n  - esp_ssg_unref() walks the source scatterlist and drops a page\n    reference for every frag, including the ubuf-owned payload frags,\n    pushing their refcount below the GUP pin bias while the pages are\n    still pinned, i.e. a use-after-free of the zerocopy pages;\n\n  - esp_output_tail() installs its destination page as frag 0 with\n    get_page() but leaves SKBFL_MANAGED_FRAG_REFS set, so\n    skb_release_data() takes the skip_unref branch and never drops that\n    reference, leaking the x-\u003exfrag page at packet rate.\n\nFix this the way every other frag-mutating site does (__ip_append_data(),\n__ip6_append_data(), tcp_sendmsg_locked()) and call\nskb_zcopy_downgrade_managed() before ESP touches the frag array: it takes\na real reference on each existing frag and clears SKBFL_MANAGED_FRAG_REFS,\nso the per-frag unref in esp_ssg_unref() and the frag release in\nskb_release_data() are both balanced and no mixed-ownership frag array is\nleft behind."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-06T08:46:53.292Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/2359264f377cdbdef2d95868cc8fb572949e48d3"
        },
        {
          "url": "https://git.kernel.org/stable/c/69a768c12398cada8528080332c822623fa7064d"
        },
        {
          "url": "https://git.kernel.org/stable/c/6508304ac2c8cdafca2f4ab915df8c707893e134"
        },
        {
          "url": "https://git.kernel.org/stable/c/6cab554f2c0f28773f712ed3a5479103f42ce844"
        },
        {
          "url": "https://git.kernel.org/stable/c/0d0845ee61c5df47cc68bc446501f48f71e8dcc6"
        },
        {
          "url": "https://git.kernel.org/stable/c/f89416eb3db151170a6f3c6dfc5239d26cdce4d2"
        }
      ],
      "title": "esp: downgrade zerocopy managed frags before mutating skb frags",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98368",
    "datePublished": "2026-10-06T08:46:53.292Z",
    "dateReserved": "2026-09-25T10:25:14.344Z",
    "dateUpdated": "2026-10-06T08:46:53.292Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-98368",
      "date": "2026-10-06",
      "epss": "0.00168",
      "percentile": "0.0556"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "defaultStatus": "unaffected",
                "product": "Linux",
                "programFiles": [
                  "net/ipv4/esp4.c",
                  "net/ipv6/esp6.c"
                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
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                    "status": "affected",
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                    "versionType": "git"
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                  {
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                    "versionType": "git"
                  },
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                    "versionType": "git"
                  },
                  {
                    "lessThan": "6cab554f2c0f28773f712ed3a5479103f42ce844",
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                    "versionType": "git"
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                    "versionType": "git"
                  }
                ]
              },
              {
                "defaultStatus": "affected",
                "product": "Linux",
                "programFiles": [
                  "net/ipv4/esp4.c",
                  "net/ipv6/esp6.c"
                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
                  {
                    "status": "affected",
                    "version": "6.0"
                  },
                  {
                    "lessThan": "6.0",
                    "status": "unaffected",
                    "version": "0",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.1.*",
                    "status": "unaffected",
                    "version": "6.1.189",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.6.*",
                    "status": "unaffected",
                    "version": "6.6.158",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.12.*",
                    "status": "unaffected",
                    "version": "6.12.112",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.18.*",
                    "status": "unaffected",
                    "version": "6.18.54",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "7.2.*",
                    "status": "unaffected",
                    "version": "7.2.8",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "*",
                    "status": "unaffected",
                    "version": "7.3-rc4",
                    "versionType": "original_commit_for_fix"
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              }
            ],
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          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nesp: downgrade zerocopy managed frags before mutating skb frags\n\nOn the out-of-place output path (esp-\u003einplace == false) ESP rewrites the\nskb frag array: esp_output_head() appends a trailer frag and\nesp_output_tail() replaces the frags with a destination page, both\nreferenced with get_page().\n\nWhen the skb carries zerocopy managed frags (SKBFL_MANAGED_FRAG_REFS) the\npayload frags are owned by the ubuf and must not be referenced or\nunreferenced individually, but ESP mutates the frag array without ever\ndowngrading the skb.  This breaks the managed-frag invariant two ways:\n\n  - esp_ssg_unref() walks the source scatterlist and drops a page\n    reference for every frag, including the ubuf-owned payload frags,\n    pushing their refcount below the GUP pin bias while the pages are\n    still pinned, i.e. a use-after-free of the zerocopy pages;\n\n  - esp_output_tail() installs its destination page as frag 0 with\n    get_page() but leaves SKBFL_MANAGED_FRAG_REFS set, so\n    skb_release_data() takes the skip_unref branch and never drops that\n    reference, leaking the x-\u003exfrag page at packet rate.\n\nFix this the way every other frag-mutating site does (__ip_append_data(),\n__ip6_append_data(), tcp_sendmsg_locked()) and call\nskb_zcopy_downgrade_managed() before ESP touches the frag array: it takes\na real reference on each existing frag and clears SKBFL_MANAGED_FRAG_REFS,\nso the per-frag unref in esp_ssg_unref() and the frag release in\nskb_release_data() are both balanced and no mixed-ownership frag array is\nleft behind."
          }
        ],
        "id": "CVE-2026-98368",
        "lastModified": "2026-10-06T09:18:31.130",
        "metrics": {},
        "published": "2026-10-06T09:18:31.130",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/0d0845ee61c5df47cc68bc446501f48f71e8dcc6"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/2359264f377cdbdef2d95868cc8fb572949e48d3"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/6508304ac2c8cdafca2f4ab915df8c707893e134"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/69a768c12398cada8528080332c822623fa7064d"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/6cab554f2c0f28773f712ed3a5479103f42ce844"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/f89416eb3db151170a6f3c6dfc5239d26cdce4d2"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    }
  }
}

FKIE_CVE-2026-98368

Vulnerability from fkie_nvd - Published: 2026-10-06 09:18 - Updated: 2026-10-06 09:18

Severity

Summary

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/0d0845ee61c5df47cc68bc446501f48f71e8dcc6
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/2359264f377cdbdef2d95868cc8fb572949e48d3
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/6508304ac2c8cdafca2f4ab915df8c707893e134
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/69a768c12398cada8528080332c822623fa7064d
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/6cab554f2c0f28773f712ed3a5479103f42ce844
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/f89416eb3db151170a6f3c6dfc5239d26cdce4d2

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv4/esp4.c",
            "net/ipv6/esp6.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "2359264f377cdbdef2d95868cc8fb572949e48d3",
              "status": "affected",
              "version": "753f1ca4e1e50248a1b760c9774d6d6b354562cc",
              "versionType": "git"
            },
            {
              "lessThan": "69a768c12398cada8528080332c822623fa7064d",
              "status": "affected",
              "version": "753f1ca4e1e50248a1b760c9774d6d6b354562cc",
              "versionType": "git"
            },
            {
              "lessThan": "6508304ac2c8cdafca2f4ab915df8c707893e134",
              "status": "affected",
              "version": "753f1ca4e1e50248a1b760c9774d6d6b354562cc",
              "versionType": "git"
            },
            {
              "lessThan": "6cab554f2c0f28773f712ed3a5479103f42ce844",
              "status": "affected",
              "version": "753f1ca4e1e50248a1b760c9774d6d6b354562cc",
              "versionType": "git"
            },
            {
              "lessThan": "0d0845ee61c5df47cc68bc446501f48f71e8dcc6",
              "status": "affected",
              "version": "753f1ca4e1e50248a1b760c9774d6d6b354562cc",
              "versionType": "git"
            },
            {
              "lessThan": "f89416eb3db151170a6f3c6dfc5239d26cdce4d2",
              "status": "affected",
              "version": "753f1ca4e1e50248a1b760c9774d6d6b354562cc",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/ipv4/esp4.c",
            "net/ipv6/esp6.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.0"
            },
            {
              "lessThan": "6.0",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.189",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.158",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.112",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.54",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc4",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nesp: downgrade zerocopy managed frags before mutating skb frags\n\nOn the out-of-place output path (esp-\u003einplace == false) ESP rewrites the\nskb frag array: esp_output_head() appends a trailer frag and\nesp_output_tail() replaces the frags with a destination page, both\nreferenced with get_page().\n\nWhen the skb carries zerocopy managed frags (SKBFL_MANAGED_FRAG_REFS) the\npayload frags are owned by the ubuf and must not be referenced or\nunreferenced individually, but ESP mutates the frag array without ever\ndowngrading the skb.  This breaks the managed-frag invariant two ways:\n\n  - esp_ssg_unref() walks the source scatterlist and drops a page\n    reference for every frag, including the ubuf-owned payload frags,\n    pushing their refcount below the GUP pin bias while the pages are\n    still pinned, i.e. a use-after-free of the zerocopy pages;\n\n  - esp_output_tail() installs its destination page as frag 0 with\n    get_page() but leaves SKBFL_MANAGED_FRAG_REFS set, so\n    skb_release_data() takes the skip_unref branch and never drops that\n    reference, leaking the x-\u003exfrag page at packet rate.\n\nFix this the way every other frag-mutating site does (__ip_append_data(),\n__ip6_append_data(), tcp_sendmsg_locked()) and call\nskb_zcopy_downgrade_managed() before ESP touches the frag array: it takes\na real reference on each existing frag and clears SKBFL_MANAGED_FRAG_REFS,\nso the per-frag unref in esp_ssg_unref() and the frag release in\nskb_release_data() are both balanced and no mixed-ownership frag array is\nleft behind."
    }
  ],
  "id": "CVE-2026-98368",
  "lastModified": "2026-10-06T09:18:31.130",
  "metrics": {},
  "published": "2026-10-06T09:18:31.130",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/0d0845ee61c5df47cc68bc446501f48f71e8dcc6"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/2359264f377cdbdef2d95868cc8fb572949e48d3"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6508304ac2c8cdafca2f4ab915df8c707893e134"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/69a768c12398cada8528080332c822623fa7064d"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6cab554f2c0f28773f712ed3a5479103f42ce844"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/f89416eb3db151170a6f3c6dfc5239d26cdce4d2"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}

GHSA-JW2Q-X793-GP2M

Vulnerability from github – Published: 2026-10-06 09:31 – Updated: 2026-10-06 09:31

Details

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

esp: downgrade zerocopy managed frags before mutating skb frags

On the out-of-place output path (esp->inplace == false) ESP rewrites the skb frag array: esp_output_head() appends a trailer frag and esp_output_tail() replaces the frags with a destination page, both referenced with get_page().

When the skb carries zerocopy managed frags (SKBFL_MANAGED_FRAG_REFS) the payload frags are owned by the ubuf and must not be referenced or unreferenced individually, but ESP mutates the frag array without ever downgrading the skb. This breaks the managed-frag invariant two ways:

esp_ssg_unref() walks the source scatterlist and drops a page reference for every frag, including the ubuf-owned payload frags, pushing their refcount below the GUP pin bias while the pages are still pinned, i.e. a use-after-free of the zerocopy pages;
esp_output_tail() installs its destination page as frag 0 with get_page() but leaves SKBFL_MANAGED_FRAG_REFS set, so skb_release_data() takes the skip_unref branch and never drops that reference, leaking the x->xfrag page at packet rate.

Fix this the way every other frag-mutating site does (__ip_append_data(), __ip6_append_data(), tcp_sendmsg_locked()) and call skb_zcopy_downgrade_managed() before ESP touches the frag array: it takes a real reference on each existing frag and clears SKBFL_MANAGED_FRAG_REFS, so the per-frag unref in esp_ssg_unref() and the frag release in skb_release_data() are both balanced and no mixed-ownership frag array is left behind.

Show details on source website

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{
  "affected": [],
  "aliases": [
    "CVE-2026-98368"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-06T09:18:31Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nesp: downgrade zerocopy managed frags before mutating skb frags\n\nOn the out-of-place output path (esp-\u003einplace == false) ESP rewrites the\nskb frag array: esp_output_head() appends a trailer frag and\nesp_output_tail() replaces the frags with a destination page, both\nreferenced with get_page().\n\nWhen the skb carries zerocopy managed frags (SKBFL_MANAGED_FRAG_REFS) the\npayload frags are owned by the ubuf and must not be referenced or\nunreferenced individually, but ESP mutates the frag array without ever\ndowngrading the skb.  This breaks the managed-frag invariant two ways:\n\n  - esp_ssg_unref() walks the source scatterlist and drops a page\n    reference for every frag, including the ubuf-owned payload frags,\n    pushing their refcount below the GUP pin bias while the pages are\n    still pinned, i.e. a use-after-free of the zerocopy pages;\n\n  - esp_output_tail() installs its destination page as frag 0 with\n    get_page() but leaves SKBFL_MANAGED_FRAG_REFS set, so\n    skb_release_data() takes the skip_unref branch and never drops that\n    reference, leaking the x-\u003exfrag page at packet rate.\n\nFix this the way every other frag-mutating site does (__ip_append_data(),\n__ip6_append_data(), tcp_sendmsg_locked()) and call\nskb_zcopy_downgrade_managed() before ESP touches the frag array: it takes\na real reference on each existing frag and clears SKBFL_MANAGED_FRAG_REFS,\nso the per-frag unref in esp_ssg_unref() and the frag release in\nskb_release_data() are both balanced and no mixed-ownership frag array is\nleft behind.",
  "id": "GHSA-jw2q-x793-gp2m",
  "modified": "2026-10-06T09:31:36Z",
  "published": "2026-10-06T09:31:36Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98368"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0d0845ee61c5df47cc68bc446501f48f71e8dcc6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2359264f377cdbdef2d95868cc8fb572949e48d3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6508304ac2c8cdafca2f4ab915df8c707893e134"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/69a768c12398cada8528080332c822623fa7064d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6cab554f2c0f28773f712ed3a5479103f42ce844"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f89416eb3db151170a6f3c6dfc5239d26cdce4d2"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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Action not permitted

CVE-2026-98368 (GCVE-0-2026-98368)

FKIE_CVE-2026-98368

GHSA-JW2Q-X793-GP2M

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