{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "cef401de7be8c4e155c6746bfccf721a4fa5fab9"
            },
            {
              "fixed": "fbeab9555564a1b98e8582cd106dfe46c4606991"
            },
            {
              "fixed": "179f1852bdedc300e373e807cc102cd81feff196"
            },
            {
              "fixed": "12401fcfb01f53ccc63ab0a3246570fe8f3105ee"
            },
            {
              "fixed": "989214c66884d70716d83dc1d0bf5e16287bf349"
            },
            {
              "fixed": "fc6eb39c55e97df2f94ad974b8a5bbcd019da2c8"
            },
            {
              "fixed": "ff375cc75f9167168db38e0464a482d5fbc8d81d"
            },
            {
              "fixed": "9bc9d6d6967a2239aa57af2aa53554eddd640d20"
            },
            {
              "fixed": "48f6a5356a33dd78e7144ae1faef95ffc990aae0"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.9.0"
            },
            {
              "fixed": "5.10.257"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.11.0"
            },
            {
              "fixed": "5.15.208"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.16.0"
            },
            {
              "fixed": "6.1.174"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.2.0"
            },
            {
              "fixed": "6.6.141"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.91"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.33"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.0.10"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43503.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: skbuff: propagate shared-frag marker through frag-transfer helpers\n\nTwo frag-transfer helpers (__pskb_copy_fclone() and skb_shift()) fail\nto propagate the SKBFL_SHARED_FRAG bit in skb_shinfo()-\u003eflags when\nmoving frags from source to destination.  __pskb_copy_fclone() defers\nthe rest of the shinfo metadata to skb_copy_header() after copying\nfrag descriptors, but that helper only carries over gso_{size,segs,\ntype} and never touches skb_shinfo()-\u003eflags; skb_shift() moves frag\ndescriptors directly and leaves flags untouched.  As a result, the\ndestination skb keeps a reference to the same externally-owned or\npage-cache-backed pages while reporting skb_has_shared_frag() as\nfalse.\n\nThe mismatch is harmful in any in-place writer that uses\nskb_has_shared_frag() to decide whether shared pages must be detoured\nthrough skb_cow_data().  ESP input is one such writer (esp4.c,\nesp6.c), and a single nft 'dup to \u003clocal\u003e' rule -- or any other\nnf_dup_ipv4() / xt_TEE caller -- is enough to land a pskb_copy()'d\nskb in esp_input() with the marker stripped, letting an unprivileged\nuser write into the page cache of a root-owned read-only file via\nauthencesn-ESN stray writes.\n\nSet SKBFL_SHARED_FRAG on the destination whenever frag descriptors\nwere actually moved from the source.  skb_copy() and skb_copy_expand()\nshare skb_copy_header() too but linearize all paged data into freshly\nallocated head storage and emerge with nr_frags == 0, so\nskb_has_shared_frag() returns false on its own; they need no change.\n\nThe same omission exists in skb_gro_receive() and skb_gro_receive_list().\nThe former moves the incoming skb's frag descriptors into the\naccumulator's last sub-skb via two paths (a direct frag-move loop and\nthe head_frag + memcpy path); the latter chains the incoming skb whole\nonto p's frag_list.  Downstream skb_segment() reads only\nskb_shinfo(p)-\u003eflags, and skb_segment_list() reuses each sub-skb's\nshinfo as the nskb -- both p and lp must carry the marker.\n\nThe same omission also exists in tcp_clone_payload(), which builds an\nMTU probe skb by moving frag descriptors from skbs on sk_write_queue\ninto a freshly allocated nskb.  The helper falls into the same family\nand warrants the same fix for consistency; no TCP TX-side in-place\nwriter is currently known to reach a user page through this gap, but\na future consumer depending on the marker would regress silently.\n\nThe same omission exists in skb_segment(): the per-iteration flag\nmerge takes only head_skb's flag, and the inner switch that rebinds\nfrag_skb to list_skb on head_skb-frags exhaustion does not fold the\nnew frag_skb's flag into nskb.  Fold frag_skb's flag at both sites\nso segments drawing frags from frag_list members carry the marker.",
  "id": "CVE-2026-43503",
  "modified": "2026-07-08T05:36:58.951888960Z",
  "published": "2026-05-23T11:44:01.103Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/12401fcfb01f53ccc63ab0a3246570fe8f3105ee"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/179f1852bdedc300e373e807cc102cd81feff196"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/48f6a5356a33dd78e7144ae1faef95ffc990aae0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/989214c66884d70716d83dc1d0bf5e16287bf349"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9bc9d6d6967a2239aa57af2aa53554eddd640d20"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fbeab9555564a1b98e8582cd106dfe46c4606991"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fc6eb39c55e97df2f94ad974b8a5bbcd019da2c8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ff375cc75f9167168db38e0464a482d5fbc8d81d"
    },
    {
      "type": "WEB",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-43503.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:19521"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:19540"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:19568"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:19569"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:19664"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:19666"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:19705"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:19711"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:19875"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:20051"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:20054"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:20087"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:20129"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:20130"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:20299"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:20593"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:21656"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:21690"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:21695"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:21702"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:23233"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:23240"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:23245"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:23468"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:23469"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:23470"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:23471"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:24814"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:25044"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:33486"
    },
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/security/cve/CVE-2026-43503"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43503.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-43503"
    },
    {
      "type": "REPORT",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2480902"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.7.5",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "net: skbuff: propagate shared-frag marker through frag-transfer helpers"
}