{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-31666",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2026-31666"
  ],
  "published": "2026-04-24T14:47:31Z",
  "summary": "btrfs: fix incorrect return value after changing leaf in lookup_extent_data_ref()",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix incorrect return value after changing leaf in lookup_extent_data_ref()\n\nAfter commit 1618aa3c2e01 (\"btrfs: simplify return variables in\nlookup_extent_data_ref()\"), the err and ret variables were merged into\na single ret variable. However, when btrfs_next_leaf() returns 0\n(success), ret is overwritten from -ENOENT to 0. If the first key in\nthe next leaf does not match (different objectid or type), the function\nreturns 0 instead of -ENOENT, making the caller believe the lookup\nsucceeded when it did not. This can lead to operations on the wrong\nextent tree item, potentially causing extent tree corruption.\n\nFix this by returning -ENOENT directly when the key does not match,\ninstead of relying on the ret variable.",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
    }
  ],
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  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-31666"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/4125a194db4a6cf91f619f38788272651cb97dce"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/450e6a685d0cad95b15f8af152057bd0bf79f50b"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/ab1e022379c3c811aa72da8eb0c7507859a1d0f5"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/316fb1b3169efb081d2db910cbbfef445afa03b9"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T13:16:28Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 7.8,
      "cvss_v3_severity": "High",
      "scenario": "AV:L - The vulnerable Btrfs extent-reference code is reached through local filesystem syscalls such as reflink/dedupe, truncate, unlink, and hole punching on a writable mounted Btrfs filesystem.\nAC:L - The trigger depends on attacker-shaped filesystem metadata and ordinary repeated file operations, not on a race or condition outside attacker control; when uncertain, the lower-complexity value is appropriate.\nPR:L - A basic unprivileged local user with write access to files on the Btrfs mount can exercise the relevant paths; no real root or init-namespace capability is required.\nUI:N - No separate victim action is required after the attacker has local access to a writable Btrfs filesystem; the attacker can issue the file operations directly.\nS:U - The impact remains within the local kernel/filesystem security authority and does not cross a VM, IOMMU, or similar security boundary.\nC:H - Incorrectly deleting or decrementing the wrong extent data reference can corrupt Btrfs extent ownership, plausibly causing stale or unrelated file data exposure through block reuse or aliasing.\nI:H - The bug can operate on the wrong extent tree item and corrupt filesystem metadata, plausibly enabling corruption or loss of arbitrary file data beyond the attacker's own intended files.\nA:H - The corrupted extent tree path can trigger transaction aborts, read-only remounts, BUG_ON/oops conditions, or persistent filesystem corruption, causing high availability impact."
    }
  }
}