FKIE_CVE-2026-98368

Vulnerability from fkie_nvd - Published: 2026-10-06 09:18 - Updated: 2026-10-06 09:18
Severity
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.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0d0845ee61c5df47cc68bc446501f48f71e8dcc6
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/2359264f377cdbdef2d95868cc8fb572949e48d3
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6508304ac2c8cdafca2f4ab915df8c707893e134
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/69a768c12398cada8528080332c822623fa7064d
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6cab554f2c0f28773f712ed3a5479103f42ce844
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f89416eb3db151170a6f3c6dfc5239d26cdce4d2
Impacted products
Vendor Product Version
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"
}



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