CVE-2026-74571 (GCVE-0-2026-74571)

Vulnerability from cvelistv5 – Published: 2026-08-15 12:28 – Updated: 2026-08-17 05:22
VLAI
Title
btrfs: skip global block reserve accounting for rescue mounts
Summary
In the Linux kernel, the following vulnerability has been resolved: btrfs: skip global block reserve accounting for rescue mounts [BUG] Mounting with rescue=ibadroots after corrupting the block group tree root triggers a NULL pointer dereference: BUG: kernel NULL pointer dereference, address: 0000000000000100 RIP: 0010:btrfs_update_global_block_rsv+0x9d/0x1c0 [btrfs] Call Trace: fill_dummy_bgs+0xd4/0x120 [btrfs] open_ctree+0xc6e/0x1ca0 [btrfs] btrfs_get_tree+0x50d/0xa40 [btrfs] The same crash occurs with a corrupted raid stripe tree root, via btrfs_read_block_groups() instead of fill_dummy_bgs(). [CAUSE] With rescue=ibadroots, btrfs_read_roots() allows the mount to continue when either root cannot be read, leaving the corresponding root pointer NULL while its on-disk feature bit remains set. btrfs_update_global_block_rsv() then dereferences the missing root based on the feature bit alone. [FIX] Rescue mounts are fully read-only and cannot start transactions, so the global reserve is never consumed. Under btrfs_is_full_ro(), mark the reserve as full and return before performing the accounting. And since we need to check if the fs is mount fully RO, export fs_is_full_ro() as btrfs_is_full_ro(), and move it to fs.h. [ Squash the fs_is_full_ro() export commit into this one. ]
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 8dbfc14fc736eb701089aff09645c3d4ad3decb1 , < 076349e4c8d11f6b58c4549976a513b2b4dc6df2 (git)
Affected: 8dbfc14fc736eb701089aff09645c3d4ad3decb1 , < 51a0e8399858621442807a26057bcd1cd3ced046 (git)
Affected: cbec34d3021d47007a0334c634f7053dbaf93d02 (git)
Affected: 1e8087589b5cf6fa17adaf57b64cf1656d77dfec (git)
Affected: 6.1.43 , < 6.2 (semver)
Affected: 6.4.8 , < 6.5 (semver)
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Linux Linux Affected: 6.5
Unaffected: 0 , < 6.5 (semver)
Unaffected: 7.1.8 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
  "containers": {
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/btrfs/block-rsv.c",
            "fs/btrfs/disk-io.c",
            "fs/btrfs/fs.h"
          ],
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          "versions": [
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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      "cpeApplicability": [
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                  "vulnerable": true
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              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: skip global block reserve accounting for rescue mounts\n\n[BUG]\nMounting with rescue=ibadroots after corrupting the block group tree\nroot triggers a NULL pointer dereference:\n\n  BUG: kernel NULL pointer dereference, address: 0000000000000100\n  RIP: 0010:btrfs_update_global_block_rsv+0x9d/0x1c0 [btrfs]\n  Call Trace:\n   fill_dummy_bgs+0xd4/0x120 [btrfs]\n   open_ctree+0xc6e/0x1ca0 [btrfs]\n   btrfs_get_tree+0x50d/0xa40 [btrfs]\n\nThe same crash occurs with a corrupted raid stripe tree root, via\nbtrfs_read_block_groups() instead of fill_dummy_bgs().\n\n[CAUSE]\nWith rescue=ibadroots, btrfs_read_roots() allows the mount to continue\nwhen either root cannot be read, leaving the corresponding root pointer\nNULL while its on-disk feature bit remains set.\n\nbtrfs_update_global_block_rsv() then dereferences the missing root based\non the feature bit alone.\n\n[FIX]\nRescue mounts are fully read-only and cannot start transactions, so the\nglobal reserve is never consumed. Under btrfs_is_full_ro(), mark the\nreserve as full and return before performing the accounting.\n\nAnd since we need to check if the fs is mount fully RO, export\nfs_is_full_ro() as btrfs_is_full_ro(), and move it to fs.h.\n\n[ Squash the fs_is_full_ro() export commit into this one. ]"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:22:00.523Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
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          "url": "https://git.kernel.org/stable/c/076349e4c8d11f6b58c4549976a513b2b4dc6df2"
        },
        {
          "url": "https://git.kernel.org/stable/c/51a0e8399858621442807a26057bcd1cd3ced046"
        }
      ],
      "title": "btrfs: skip global block reserve accounting for rescue mounts",
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74571",
    "datePublished": "2026-08-15T12:28:10.711Z",
    "dateReserved": "2026-08-15T05:44:03.917Z",
    "dateUpdated": "2026-08-17T05:22:00.523Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-74571",
      "date": "2026-08-18",
      "epss": "0.00145",
      "percentile": "0.04319"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-74571\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-08-15T13:18:02.733\",\"lastModified\":\"2026-08-17T06:19:55.417\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nbtrfs: skip global block reserve accounting for rescue mounts\\n\\n[BUG]\\nMounting with rescue=ibadroots after corrupting the block group tree\\nroot triggers a NULL pointer dereference:\\n\\n  BUG: kernel NULL pointer dereference, address: 0000000000000100\\n  RIP: 0010:btrfs_update_global_block_rsv+0x9d/0x1c0 [btrfs]\\n  Call Trace:\\n   fill_dummy_bgs+0xd4/0x120 [btrfs]\\n   open_ctree+0xc6e/0x1ca0 [btrfs]\\n   btrfs_get_tree+0x50d/0xa40 [btrfs]\\n\\nThe same crash occurs with a corrupted raid stripe tree root, via\\nbtrfs_read_block_groups() instead of fill_dummy_bgs().\\n\\n[CAUSE]\\nWith rescue=ibadroots, btrfs_read_roots() allows the mount to continue\\nwhen either root cannot be read, leaving the corresponding root pointer\\nNULL while its on-disk feature bit remains set.\\n\\nbtrfs_update_global_block_rsv() then dereferences the missing root based\\non the feature bit alone.\\n\\n[FIX]\\nRescue mounts are fully read-only and cannot start transactions, so the\\nglobal reserve is never consumed. Under btrfs_is_full_ro(), mark the\\nreserve as full and return before performing the accounting.\\n\\nAnd since we need to check if the fs is mount fully RO, export\\nfs_is_full_ro() as btrfs_is_full_ro(), and move it to fs.h.\\n\\n[ Squash the fs_is_full_ro() export commit into this one. ]\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/btrfs/block-rsv.c\",\"fs/btrfs/disk-io.c\",\"fs/btrfs/fs.h\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"8dbfc14fc736eb701089aff09645c3d4ad3decb1\",\"lessThan\":\"076349e4c8d11f6b58c4549976a513b2b4dc6df2\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"8dbfc14fc736eb701089aff09645c3d4ad3decb1\",\"lessThan\":\"51a0e8399858621442807a26057bcd1cd3ced046\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"cbec34d3021d47007a0334c634f7053dbaf93d02\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"1e8087589b5cf6fa17adaf57b64cf1656d77dfec\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"6.1.43\",\"lessThan\":\"6.2\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"6.4.8\",\"lessThan\":\"6.5\",\"versionType\":\"semver\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"fs/btrfs/block-rsv.c\",\"fs/btrfs/disk-io.c\",\"fs/btrfs/fs.h\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.5\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.5\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.8\",\"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/076349e4c8d11f6b58c4549976a513b2b4dc6df2\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/51a0e8399858621442807a26057bcd1cd3ced046\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "suse_vex": {
      "aggregate_severity": "not set",
      "current_release_date": "2026-08-15T23:49:56Z",
      "cve": "CVE-2026-74571",
      "id": "CVE-2026-74571",
      "initial_release_date": "2026-08-15T23:49:56Z",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-74571",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-74571.json",
      "version": "2"
    }
  }
}



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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.

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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.