Vulnerability-Lookup

GHSA-GR86-25PQ-RHR2

Vulnerability from github – Published: 2026-08-12 00:31 – Updated: 2026-08-12 00:31

Details

In the Linux kernel, the following vulnerability has been resolved:

btrfs: don't propagate EXTENT_FLAG_LOGGING to split extent maps

When btrfs_drop_extent_map_range() splits an extent map, the new split maps inherit the original map's flags through a local 'flags' variable. Commit f86f7a75e2fb ("btrfs: use the flags of an extent map to identify the compression type") changed the EXTENT_FLAG_LOGGING clearing to operate on em->flags instead of that local 'flags' copy, so a split of an extent map that is currently being logged wrongly inherits EXTENT_FLAG_LOGGING.

The flag is then never cleared on the split, and when it is freed while still on the inode's modified_extents list (for example by the extent map shrinker) it trips the WARN_ON(!list_empty(&em->list)) in btrfs_free_extent_map() and leads to a use-after-free.

Clear EXTENT_FLAG_LOGGING from the local 'flags' copy used for the splits and only clear EXTENT_FLAG_PINNED from em->flags, restoring the behaviour prior to f86f7a75e2fb.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-68442"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-12T00:17:44Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: don\u0027t propagate EXTENT_FLAG_LOGGING to split extent maps\n\nWhen btrfs_drop_extent_map_range() splits an extent map, the new split\nmaps inherit the original map\u0027s flags through a local \u0027flags\u0027 variable.\nCommit f86f7a75e2fb (\"btrfs: use the flags of an extent map to identify\nthe compression type\") changed the EXTENT_FLAG_LOGGING clearing to\noperate on em-\u003eflags instead of that local \u0027flags\u0027 copy, so a split of\nan extent map that is currently being logged wrongly inherits\nEXTENT_FLAG_LOGGING.\n\nThe flag is then never cleared on the split, and when it is freed while\nstill on the inode\u0027s modified_extents list (for example by the extent\nmap shrinker) it trips the WARN_ON(!list_empty(\u0026em-\u003elist)) in\nbtrfs_free_extent_map() and leads to a use-after-free.\n\nClear EXTENT_FLAG_LOGGING from the local \u0027flags\u0027 copy used for the\nsplits and only clear EXTENT_FLAG_PINNED from em-\u003eflags, restoring the\nbehaviour prior to f86f7a75e2fb.",
  "id": "GHSA-gr86-25pq-rhr2",
  "modified": "2026-08-12T00:31:13Z",
  "published": "2026-08-12T00:31:13Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-68442"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0e465c63f103a5ce6849614d6bda048d70eebec8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2a9246a424f45f33a1b8367052611ebe874868ad"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5eff4d5b17fa1950e80bfd1ba43dc0699e61a644"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9304713b70e7e1450e3a76e758836fe5391bfa95"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-68442 (GCVE-0-2026-68442)

Vulnerability from cvelistv5 – Published: 2026-08-12 00:07 – Updated: 2026-08-12 00:07

Title

btrfs: don't propagate EXTENT_FLAG_LOGGING to split extent maps

Summary

In the Linux kernel, the following vulnerability has been resolved: btrfs: don't propagate EXTENT_FLAG_LOGGING to split extent maps When btrfs_drop_extent_map_range() splits an extent map, the new split maps inherit the original map's flags through a local 'flags' variable. Commit f86f7a75e2fb ("btrfs: use the flags of an extent map to identify the compression type") changed the EXTENT_FLAG_LOGGING clearing to operate on em->flags instead of that local 'flags' copy, so a split of an extent map that is currently being logged wrongly inherits EXTENT_FLAG_LOGGING. The flag is then never cleared on the split, and when it is freed while still on the inode's modified_extents list (for example by the extent map shrinker) it trips the WARN_ON(!list_empty(&em->list)) in btrfs_free_extent_map() and leads to a use-after-free. Clear EXTENT_FLAG_LOGGING from the local 'flags' copy used for the splits and only clear EXTENT_FLAG_PINNED from em->flags, restoring the behaviour prior to f86f7a75e2fb.

Severity

No CVSS data available.

Assigner

Linux

References

4 references

URL	Tags
https://git.kernel.org/stable/c/2a9246a424f45f33a…
https://git.kernel.org/stable/c/9304713b70e7e1450…
https://git.kernel.org/stable/c/0e465c63f103a5ce6…
https://git.kernel.org/stable/c/5eff4d5b17fa1950e…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9 , < 2a9246a424f45f33a1b8367052611ebe874868ad (git) Affected: f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9 , < 9304713b70e7e1450e3a76e758836fe5391bfa95 (git) Affected: f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9 , < 0e465c63f103a5ce6849614d6bda048d70eebec8 (git) Affected: f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9 , < 5eff4d5b17fa1950e80bfd1ba43dc0699e61a644 (git)
Linux	Linux	Affected: 6.8 Unaffected: 0 , < 6.8 (semver) Unaffected: 6.12.101 , ≤ 6.12.* (semver) Unaffected: 6.18.42 , ≤ 6.18.* (semver) Unaffected: 7.1.6 , ≤ 7.1.* (semver) Unaffected: 7.2-rc5 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/btrfs/extent_map.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "2a9246a424f45f33a1b8367052611ebe874868ad",
              "status": "affected",
              "version": "f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9",
              "versionType": "git"
            },
            {
              "lessThan": "9304713b70e7e1450e3a76e758836fe5391bfa95",
              "status": "affected",
              "version": "f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9",
              "versionType": "git"
            },
            {
              "lessThan": "0e465c63f103a5ce6849614d6bda048d70eebec8",
              "status": "affected",
              "version": "f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9",
              "versionType": "git"
            },
            {
              "lessThan": "5eff4d5b17fa1950e80bfd1ba43dc0699e61a644",
              "status": "affected",
              "version": "f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/btrfs/extent_map.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.8"
            },
            {
              "lessThan": "6.8",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.101",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.42",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2-rc5",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.101",
                  "versionStartIncluding": "6.8",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: don\u0027t propagate EXTENT_FLAG_LOGGING to split extent maps\n\nWhen btrfs_drop_extent_map_range() splits an extent map, the new split\nmaps inherit the original map\u0027s flags through a local \u0027flags\u0027 variable.\nCommit f86f7a75e2fb (\"btrfs: use the flags of an extent map to identify\nthe compression type\") changed the EXTENT_FLAG_LOGGING clearing to\noperate on em-\u003eflags instead of that local \u0027flags\u0027 copy, so a split of\nan extent map that is currently being logged wrongly inherits\nEXTENT_FLAG_LOGGING.\n\nThe flag is then never cleared on the split, and when it is freed while\nstill on the inode\u0027s modified_extents list (for example by the extent\nmap shrinker) it trips the WARN_ON(!list_empty(\u0026em-\u003elist)) in\nbtrfs_free_extent_map() and leads to a use-after-free.\n\nClear EXTENT_FLAG_LOGGING from the local \u0027flags\u0027 copy used for the\nsplits and only clear EXTENT_FLAG_PINNED from em-\u003eflags, restoring the\nbehaviour prior to f86f7a75e2fb."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-12T00:07:31.981Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
        {
          "url": "https://git.kernel.org/stable/c/5eff4d5b17fa1950e80bfd1ba43dc0699e61a644"
        }
      ],
      "title": "btrfs: don\u0027t propagate EXTENT_FLAG_LOGGING to split extent maps",
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        "engine": "bippy-1.2.0"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-68442",
    "datePublished": "2026-08-12T00:07:31.981Z",
    "dateReserved": "2026-07-30T09:28:09.394Z",
    "dateUpdated": "2026-08-12T00:07:31.981Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.

Action not permitted

GHSA-GR86-25PQ-RHR2

CVE-2026-68442 (GCVE-0-2026-68442)

Tags

Sightings

Nomenclature