CVE-2026-63817 (GCVE-0-2026-63817)
Vulnerability from cvelistv5
Published
2026-07-19 12:02
Modified
2026-08-17 04:51
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: f2fs: validate compress cache inode only when enabled F2FS_COMPRESS_INO() uses NM_I(sbi)->max_nid as the synthetic inode number for the compressed page cache inode. That inode only exists when the compress_cache mount option is enabled. When compress_cache is disabled, max_nid is outside the valid inode range. A corrupted directory entry that points to ino == max_nid should therefore be rejected by f2fs_check_nid_range(). However, is_meta_ino() currently treats F2FS_COMPRESS_INO() as a meta inode unconditionally, so f2fs_iget() bypasses do_read_inode() and its nid range check, and instantiates a fake internal inode instead. Gate the compressed cache inode case on COMPRESS_CACHE, matching f2fs_init_compress_inode(). With compress_cache disabled, ino == max_nid now follows the normal inode path and is rejected as an out-of-range nid.
References
Impacted products
Vendor Product Version
Linux Linux Version: 6ce19aff0b8cd386860855185c6cd79337fc4d2b
Version: 6ce19aff0b8cd386860855185c6cd79337fc4d2b
Version: 6ce19aff0b8cd386860855185c6cd79337fc4d2b
Version: 6ce19aff0b8cd386860855185c6cd79337fc4d2b
Version: 6ce19aff0b8cd386860855185c6cd79337fc4d2b
Version: 6ce19aff0b8cd386860855185c6cd79337fc4d2b
Version: 6ce19aff0b8cd386860855185c6cd79337fc4d2b
Version: a23706426da9b611be5beae0f3faa260fb453b4e
Version: 5.13.19   ≤
Create a notification for this product.
Show details on NVD website

To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/f2fs/inode.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "fcc051d377a9701a452e7663a1a8223c26225df9",
              "status": "affected",
              "version": "6ce19aff0b8cd386860855185c6cd79337fc4d2b",
              "versionType": "git"
            },
            {
              "lessThan": "29115b8c9172d34e67ab26cc4f6c209b7a236d7a",
              "status": "affected",
              "version": "6ce19aff0b8cd386860855185c6cd79337fc4d2b",
              "versionType": "git"
            },
            {
              "lessThan": "13e4b59d3a9413f66f116fa6c4828519b960a5ea",
              "status": "affected",
              "version": "6ce19aff0b8cd386860855185c6cd79337fc4d2b",
              "versionType": "git"
            },
            {
              "lessThan": "16161444c30d8dff9428abbae42b72ce4e32a932",
              "status": "affected",
              "version": "6ce19aff0b8cd386860855185c6cd79337fc4d2b",
              "versionType": "git"
            },
            {
              "lessThan": "77f216ff9ce5cde8eed9f6d12707e906dffdc9f7",
              "status": "affected",
              "version": "6ce19aff0b8cd386860855185c6cd79337fc4d2b",
              "versionType": "git"
            },
            {
              "lessThan": "0969926d987bbde9a1aa49da317582ba37095805",
              "status": "affected",
              "version": "6ce19aff0b8cd386860855185c6cd79337fc4d2b",
              "versionType": "git"
            },
            {
              "lessThan": "5073c66a96a9c23c0c2533ed4ed06e42f9021208",
              "status": "affected",
              "version": "6ce19aff0b8cd386860855185c6cd79337fc4d2b",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "a23706426da9b611be5beae0f3faa260fb453b4e",
              "versionType": "git"
            },
            {
              "lessThan": "5.14",
              "status": "affected",
              "version": "5.13.19",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/f2fs/inode.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.14"
            },
            {
              "lessThan": "5.14",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.212",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.177",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.144",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.95",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.38",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.212",
                  "versionStartIncluding": "5.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.177",
                  "versionStartIncluding": "5.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.144",
                  "versionStartIncluding": "5.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.95",
                  "versionStartIncluding": "5.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.38",
                  "versionStartIncluding": "5.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.3",
                  "versionStartIncluding": "5.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "5.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "5.13.19",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: validate compress cache inode only when enabled\n\nF2FS_COMPRESS_INO() uses NM_I(sbi)-\u003emax_nid as the synthetic inode\nnumber for the compressed page cache inode. That inode only exists when\nthe compress_cache mount option is enabled.\n\nWhen compress_cache is disabled, max_nid is outside the valid inode\nrange. A corrupted directory entry that points to ino == max_nid should\ntherefore be rejected by f2fs_check_nid_range(). However, is_meta_ino()\ncurrently treats F2FS_COMPRESS_INO() as a meta inode unconditionally,\nso f2fs_iget() bypasses do_read_inode() and its nid range check, and\ninstantiates a fake internal inode instead.\n\nGate the compressed cache inode case on COMPRESS_CACHE, matching\nf2fs_init_compress_inode(). With compress_cache disabled, ino ==\nmax_nid now follows the normal inode path and is rejected as an\nout-of-range nid."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The bug is reached through local VFS operations (open/lookup, get_parent, mount-time recovery, and background GC) on a mounted F2FS filesystem; there is no direct network packet handler, though NFS export is a secondary path still requiring local filesystem access to plant corruption.\nAC:L - An attacker can deterministically craft an F2FS image with a directory entry pointing at ino=max_nid (known at image creation) and reliably trigger f2fs_iget() on mount or lookup without depending on uncontrollable runtime conditions.\nPR:L - Triggering requires mounting or writing to F2FS, which needs CAP_SYS_ADMIN but is obtainable by an unprivileged user via user namespaces; planting a corrupted dentry also requires only low-privilege write access to the filesystem.\nUI:N - Once a crafted or corrupted filesystem is in place, exploitation is driven entirely by attacker-initiated syscalls (mount, lookup, open) or automatic kernel paths (GC, recovery) with no victim interaction required.\nS:U - Impact is confined to kernel memory/filesystem integrity on the host running the affected F2FS code; it does not cross a VM, container, or IOMMU security boundary in the manner of a guest-to-host escape.\nC:H - Bypassing inode validation instantiates a mis-typed, uninitialized inode that subsequent f2fs data and node paths operate on, creating a type-confusion condition that can be leveraged for arbitrary kernel memory read primitives.\nI:H - The fake compress-cache inode is wired with compress address_space operations and skips normal inode teardown, enabling type confusion that can be abused for arbitrary kernel memory writes or control-flow hijacking.\nA:H - Operating on an invalid synthetic inode in GC, recovery, or lookup paths can trigger kernel oops, EFSCORRUPTED error handling, or filesystem panic (errors=panic), causing denial of service or system crash."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:51:24.577Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/fcc051d377a9701a452e7663a1a8223c26225df9"
        },
        {
          "url": "https://git.kernel.org/stable/c/29115b8c9172d34e67ab26cc4f6c209b7a236d7a"
        },
        {
          "url": "https://git.kernel.org/stable/c/13e4b59d3a9413f66f116fa6c4828519b960a5ea"
        },
        {
          "url": "https://git.kernel.org/stable/c/16161444c30d8dff9428abbae42b72ce4e32a932"
        },
        {
          "url": "https://git.kernel.org/stable/c/77f216ff9ce5cde8eed9f6d12707e906dffdc9f7"
        },
        {
          "url": "https://git.kernel.org/stable/c/0969926d987bbde9a1aa49da317582ba37095805"
        },
        {
          "url": "https://git.kernel.org/stable/c/5073c66a96a9c23c0c2533ed4ed06e42f9021208"
        }
      ],
      "title": "f2fs: validate compress cache inode only when enabled",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-63817",
    "datePublished": "2026-07-19T12:02:16.441Z",
    "dateReserved": "2026-07-19T07:54:57.014Z",
    "dateUpdated": "2026-08-17T04:51:24.577Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.