CVE-2026-80530 (GCVE-0-2026-80530)

Vulnerability from cvelistv5 – Published: 2026-08-26 14:37 – Updated: 2026-08-27 05:01
VLAI
Title
xfs: fix exchange-range reflink flag clearing issue with INO1_WRITTEN
Summary
In the Linux kernel, the following vulnerability has been resolved: xfs: fix exchange-range reflink flag clearing issue with INO1_WRITTEN When exchanging two full-file ranges, xmi_can_exchange_reflink_flags() can move the reflink inode flag from the file that currently has it to the other file, as long as exactly one side is marked. This assumes that the file contents, and therefore all shared extents, are exchanged. That assumption is not true when XFS_EXCHMAPS_INO1_WRITTEN is set. xfs_exchmaps_can_skip_mapping() can skip hole and unwritten mappings from file1, so an exchange can complete without moving every mapping that the earlier flag-swap decision accounted for. In that case the post-operation cleanup can clear the reflink flag from an inode that still owns shared written extents. Later writes then take the non-reflink write path and may update blocks that should still have been protected by CoW, which shows up as data corruption between reflink-related files. Fix this by disabling the reflink flag exchange whenever XFS_EXCHMAPS_INO1_WRITTEN is requested. The contents exchange can still proceed; the conservative outcome is that both inodes keep the reflink flag. The regular reflink flag cleanup path can drop the extra flag later once the inode no longer has shared extents.
Severity
7.1 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 966ceafc7a437105ecfe1cadb3747b2965a260ca , < 2efbd8890b53f4756fdc7b0ef346fa514ffb7d66 (git)
Affected: 966ceafc7a437105ecfe1cadb3747b2965a260ca , < 0f27b22343b63e10773e6781344640c2c753eec3 (git)
Affected: 966ceafc7a437105ecfe1cadb3747b2965a260ca , < 03c9c9116e6da641424681f705698d7f5e2128e0 (git)
Affected: 966ceafc7a437105ecfe1cadb3747b2965a260ca , < b2d5a81dae385333f9734910277fbf94c78bd17f (git)
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Linux Linux Affected: 6.10
Unaffected: 0 , < 6.10 (semver)
Unaffected: 6.12.105 , ≤ 6.12.* (semver)
Unaffected: 6.18.46 , ≤ 6.18.* (semver)
Unaffected: 7.1.10 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/xfs/libxfs/xfs_exchmaps.c"
          ],
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          "vendor": "Linux",
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          "product": "Linux",
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "version": "6.10"
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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              "versionType": "semver"
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              "status": "unaffected",
              "version": "6.18.46",
              "versionType": "semver"
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              "version": "7.1.10",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
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      "cpeApplicability": [
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                  "vulnerable": true
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              "negate": false,
              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfs: fix exchange-range reflink flag clearing issue with INO1_WRITTEN\n\nWhen exchanging two full-file ranges, xmi_can_exchange_reflink_flags()\ncan move the reflink inode flag from the file that currently has it to\nthe other file, as long as exactly one side is marked.  This assumes\nthat the file contents, and therefore all shared extents, are exchanged.\n\nThat assumption is not true when XFS_EXCHMAPS_INO1_WRITTEN is set.\nxfs_exchmaps_can_skip_mapping() can skip hole and unwritten mappings\nfrom file1, so an exchange can complete without moving every mapping\nthat the earlier flag-swap decision accounted for.  In that case the\npost-operation cleanup can clear the reflink flag from an inode that\nstill owns shared written extents.  Later writes then take the\nnon-reflink write path and may update blocks that should still have\nbeen protected by CoW, which shows up as data corruption between\nreflink-related files.\n\nFix this by disabling the reflink flag exchange whenever\nXFS_EXCHMAPS_INO1_WRITTEN is requested.  The contents exchange can still\nproceed; the conservative outcome is that both inodes keep the reflink\nflag.  The regular reflink flag cleanup path can drop the extra flag\nlater once the inode no longer has shared extents."
        }
      ],
      "metrics": [
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The flaw is only reachable via xfs_ioc_exchange_range()/xfs_ioc_commit_range() through XFS_IOC_EXCHANGE_RANGE or XFS_IOC_COMMIT_RANGE ioctl on open XFS file descriptors; there is no nfsd, ksmbd, or network packet path to xfs_exchmaps_clear_reflink().\nAC:L - A local attacker can craft reflinked files with hole/unwritten mappings, open both files read-write, and call exchange-range with XFS_EXCHANGE_RANGE_FILE1_WRITTEN|TO_EOF to deterministically skip mappings and trigger incorrect post-op reflink-flag clearing.\nPR:L - XFS_IOC_EXCHANGE_RANGE has no CAP_SYS_ADMIN gate and only requires DAC write on both exchanged files plus read access to reflink-clone a victim file; unprivileged users on shared multi-tenant XFS mounts meet this without init-namespace root.\nUI:N - Exploitation requires only the attacker\u0027s own ioctl calls on files they control; no separate victim must mount media, click prompts, or perform actions beyond storing readable data the attacker reflinks.\nS:U - Impact is on-disk data corruption or commingling between reflink-linked files within the same host kernel/filesystem authority; it does not cross VM, container network, or IOMMU boundaries like a hypervisor escape.\nC:H - Clearing the reflink inode flag while shared written extents remain breaks CoW isolation, so subsequent non-reflink writes can commingle or overwrite blocks still linked to other users\u0027 reflink clones, leaking data CoW should have kept private.\nI:H - After the incorrect reflink-flag clear, writes take the non-reflink path and directly modify shared storage blocks, letting an attacker corrupt content in other users\u0027 reflink-linked files without write permission to those inodes.\nA:N - The failure is logical metadata mishandling causing cross-file data corruption; it does not trigger kernel oops, panic, BUG_ON, or hang, and the fix commit describes only data corruption between reflink-related files, not system unavailability."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-27T05:01:24.159Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
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          "url": "https://git.kernel.org/stable/c/2efbd8890b53f4756fdc7b0ef346fa514ffb7d66"
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          "url": "https://git.kernel.org/stable/c/0f27b22343b63e10773e6781344640c2c753eec3"
        },
        {
          "url": "https://git.kernel.org/stable/c/03c9c9116e6da641424681f705698d7f5e2128e0"
        },
        {
          "url": "https://git.kernel.org/stable/c/b2d5a81dae385333f9734910277fbf94c78bd17f"
        }
      ],
      "title": "xfs: fix exchange-range reflink flag clearing issue with INO1_WRITTEN",
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        "engine": "bippy-1.2.0"
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-80530",
    "datePublished": "2026-08-26T14:37:07.990Z",
    "dateReserved": "2026-08-26T14:34:25.764Z",
    "dateUpdated": "2026-08-27T05:01:24.159Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2",
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      "date": "2026-09-01",
      "epss": "0.00126",
      "percentile": "0.02555"
    },
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-27T06:33:36+00:00",
      "cve": "CVE-2026-80530",
      "id": "CVE-2026-80530",
      "initial_release_date": "2026-08-26T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "90",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: xfs: fix exchange-range reflink flag clearing issue with INO1_WRITTEN",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80530.json",
      "version": "3"
    }
  }
}



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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

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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.