GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

CVE-2026-74307 (GCVE-0-2026-74307)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:58 – Updated: 2026-08-17 05:16
VLAI
Title
ext4: validate donor file superblock early in EXT4_IOC_MOVE_EXT
Summary
In the Linux kernel, the following vulnerability has been resolved: ext4: validate donor file superblock early in EXT4_IOC_MOVE_EXT Reject the EXT4_IOC_MOVE_EXT ioctl early if the donor file does not belong to the same superblock as the original file. Currently, this validation is performed inside ext4_move_extents() by mext_check_validity(), but only after lock_two_nondirectories() has already acquired the inode locks. When the donor fd refers to a file on a different filesystem (e.g., overlayfs), this late validation creates a circular lock dependency: CPU0 (overlayfs write) CPU1 (ext4 ioctl) ---- ---- inode_lock(ovl_inode) mnt_want_write_file(filp) sb_start_write(ext4_sb) [sb_writers] backing_file_write_iter() vfs_iter_write(real_file) file_start_write(real_file) sb_start_write(ext4_sb) [blocked by freeze] lock_two_nondirectories() inode_lock(ovl_inode) [blocked] With a concurrent freeze operation holding sb_writers write side, this forms a deadlock cycle: CPU0 waits for freeze to complete, freeze waits for CPU1's sb_writers reader to exit, CPU1 waits for CPU0's inode lock. Since EXT4_IOC_MOVE_EXT exchanges physical extents between two files, it fundamentally requires both files to reside on the same ext4 filesystem. Moving the superblock check before any lock acquisition is both semantically correct and eliminates the circular dependency by ensuring that cross-filesystem donor fds are rejected before sb_writers or inode locks are taken.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a , < 74796e886ca39fcb0d3fd36ea6a39c62784ab6fb (git)
Affected: fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a , < fb52013cad9e9b7d3a6a14ea1bcd841e41da7c6c (git)
Affected: fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a , < c143957520c6c9b5cd72e0de8b52b814f0c576fe (git)
guessed Create a notification for this product.
Linux Linux Affected: 3.18
Unaffected: 0 , < 3.18 (semver)
Unaffected: 6.12.97 , ≤ 6.12.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/ext4/ioctl.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "74796e886ca39fcb0d3fd36ea6a39c62784ab6fb",
              "status": "affected",
              "version": "fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a",
              "versionType": "git"
            },
            {
              "lessThan": "fb52013cad9e9b7d3a6a14ea1bcd841e41da7c6c",
              "status": "affected",
              "version": "fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a",
              "versionType": "git"
            },
            {
              "lessThan": "c143957520c6c9b5cd72e0de8b52b814f0c576fe",
              "status": "affected",
              "version": "fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/ext4/ioctl.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3.18"
            },
            {
              "lessThan": "3.18",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.97",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.5",
              "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": "6.12.97",
                  "versionStartIncluding": "3.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.5",
                  "versionStartIncluding": "3.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "3.18",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: validate donor file superblock early in EXT4_IOC_MOVE_EXT\n\nReject the EXT4_IOC_MOVE_EXT ioctl early if the donor file does not\nbelong to the same superblock as the original file.  Currently, this\nvalidation is performed inside ext4_move_extents() by\nmext_check_validity(), but only after lock_two_nondirectories() has\nalready acquired the inode locks.  When the donor fd refers to a file\non a different filesystem (e.g., overlayfs), this late validation\ncreates a circular lock dependency:\n\n  CPU0 (overlayfs write)            CPU1 (ext4 ioctl)\n  ----                              ----\n  inode_lock(ovl_inode)\n                                    mnt_want_write_file(filp)\n                                      sb_start_write(ext4_sb)   [sb_writers]\n    backing_file_write_iter()\n      vfs_iter_write(real_file)\n        file_start_write(real_file)\n          sb_start_write(ext4_sb)   [blocked by freeze]\n                                    lock_two_nondirectories()\n                                      inode_lock(ovl_inode)     [blocked]\n\nWith a concurrent freeze operation holding sb_writers write side, this\nforms a deadlock cycle: CPU0 waits for freeze to complete, freeze waits\nfor CPU1\u0027s sb_writers reader to exit, CPU1 waits for CPU0\u0027s inode lock.\n\nSince EXT4_IOC_MOVE_EXT exchanges physical extents between two files,\nit fundamentally requires both files to reside on the same ext4\nfilesystem.  Moving the superblock check before any lock acquisition\nis both semantically correct and eliminates the circular dependency\nby ensuring that cross-filesystem donor fds are rejected before\nsb_writers or inode locks are taken."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:16:56.046Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/74796e886ca39fcb0d3fd36ea6a39c62784ab6fb"
        },
        {
          "url": "https://git.kernel.org/stable/c/fb52013cad9e9b7d3a6a14ea1bcd841e41da7c6c"
        },
        {
          "url": "https://git.kernel.org/stable/c/c143957520c6c9b5cd72e0de8b52b814f0c576fe"
        }
      ],
      "title": "ext4: validate donor file superblock early in EXT4_IOC_MOVE_EXT",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74307",
    "datePublished": "2026-08-15T05:58:07.969Z",
    "dateReserved": "2026-08-15T05:44:03.883Z",
    "dateUpdated": "2026-08-17T05:16:56.046Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-74307",
      "date": "2026-09-10",
      "epss": "0.00166",
      "percentile": "0.06145"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-74307\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-08-15T06:22:30.500\",\"lastModified\":\"2026-08-17T06:19:24.907\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\next4: validate donor file superblock early in EXT4_IOC_MOVE_EXT\\n\\nReject the EXT4_IOC_MOVE_EXT ioctl early if the donor file does not\\nbelong to the same superblock as the original file.  Currently, this\\nvalidation is performed inside ext4_move_extents() by\\nmext_check_validity(), but only after lock_two_nondirectories() has\\nalready acquired the inode locks.  When the donor fd refers to a file\\non a different filesystem (e.g., overlayfs), this late validation\\ncreates a circular lock dependency:\\n\\n  CPU0 (overlayfs write)            CPU1 (ext4 ioctl)\\n  ----                              ----\\n  inode_lock(ovl_inode)\\n                                    mnt_want_write_file(filp)\\n                                      sb_start_write(ext4_sb)   [sb_writers]\\n    backing_file_write_iter()\\n      vfs_iter_write(real_file)\\n        file_start_write(real_file)\\n          sb_start_write(ext4_sb)   [blocked by freeze]\\n                                    lock_two_nondirectories()\\n                                      inode_lock(ovl_inode)     [blocked]\\n\\nWith a concurrent freeze operation holding sb_writers write side, this\\nforms a deadlock cycle: CPU0 waits for freeze to complete, freeze waits\\nfor CPU1\u0027s sb_writers reader to exit, CPU1 waits for CPU0\u0027s inode lock.\\n\\nSince EXT4_IOC_MOVE_EXT exchanges physical extents between two files,\\nit fundamentally requires both files to reside on the same ext4\\nfilesystem.  Moving the superblock check before any lock acquisition\\nis both semantically correct and eliminates the circular dependency\\nby ensuring that cross-filesystem donor fds are rejected before\\nsb_writers or inode locks are taken.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/ext4/ioctl.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a\",\"lessThan\":\"74796e886ca39fcb0d3fd36ea6a39c62784ab6fb\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a\",\"lessThan\":\"fb52013cad9e9b7d3a6a14ea1bcd841e41da7c6c\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a\",\"lessThan\":\"c143957520c6c9b5cd72e0de8b52b814f0c576fe\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"fs/ext4/ioctl.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"3.18\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"3.18\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.97\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.5\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/74796e886ca39fcb0d3fd36ea6a39c62784ab6fb\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/c143957520c6c9b5cd72e0de8b52b814f0c576fe\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/fb52013cad9e9b7d3a6a14ea1bcd841e41da7c6c\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-20T16:38:00+00:00",
      "cve": "CVE-2026-74307",
      "id": "CVE-2026-74307",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "246",
      "product_status:known_not_affected": "28",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ext4: validate donor file superblock early in EXT4_IOC_MOVE_EXT",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-74307.json",
      "version": "3"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.