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

CVE-2026-64031 (GCVE-0-2026-64031)

Vulnerability from cvelistv5 – Published: 2026-07-19 15:39 – Updated: 2026-08-05 12:38
VLAI
Title
erofs: fix managed cache race for unaligned extents
Summary
In the Linux kernel, the following vulnerability has been resolved: erofs: fix managed cache race for unaligned extents After unaligned compressed extents were introduced, the following race could occur: [Thread 1] [Thread 2] (z_erofs_fill_bio_vec) <handle a Z_EROFS_PREALLOCATED_FOLIO folio> ... filemap_add_folio (1) (z_erofs_bind_cache) <the same folio is found..> .. .. folio_attach_private (2) filemap_add_folio (3) again Since (1) is executed but (2) hasn't been executed yet, it's possible that another thread finds the same managed folio in z_erofs_bind_cache() for a different pcluster and calls filemap_add_folio() again since folio->private is still Z_EROFS_PREALLOCATED_FOLIO. Fix this by explicitly clearing folio->private before making the folio visible in the managed cache so that another pcluster can simply wait on the locked managed folio as what we did for other shared cases [1]. This only impacts unaligned data compression (`-E48bit` with zstd, for example). [1] Commit 9e2f9d34dd12 ("erofs: handle overlapped pclusters out of crafted images properly") was originally introduced to handle crafted overlapped extents, but it addresses unaligned extents as well.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 7361d1e3763baaf7b9349c576137851458ad38d1 , < 425d32d6288d7d845e486af9419bbedccd8c9103 (git)
Affected: 7361d1e3763baaf7b9349c576137851458ad38d1 , < 038166f873c4caf6e85cfd4ea0c5a5ba297b4e8b (git)
Affected: 7361d1e3763baaf7b9349c576137851458ad38d1 , < 649932fc3815eda2f24eb4de4b3a5e94886ee0b9 (git)
guessed Create a notification for this product.
Linux Linux Affected: 6.15
Unaffected: 0 , < 6.15 (semver)
Unaffected: 6.18.34 , ≤ 6.18.* (semver)
Unaffected: 7.0.11 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (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/erofs/zdata.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "425d32d6288d7d845e486af9419bbedccd8c9103",
              "status": "affected",
              "version": "7361d1e3763baaf7b9349c576137851458ad38d1",
              "versionType": "git"
            },
            {
              "lessThan": "038166f873c4caf6e85cfd4ea0c5a5ba297b4e8b",
              "status": "affected",
              "version": "7361d1e3763baaf7b9349c576137851458ad38d1",
              "versionType": "git"
            },
            {
              "lessThan": "649932fc3815eda2f24eb4de4b3a5e94886ee0b9",
              "status": "affected",
              "version": "7361d1e3763baaf7b9349c576137851458ad38d1",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/erofs/zdata.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.15"
            },
            {
              "lessThan": "6.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.34",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.34",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0.11",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nerofs: fix managed cache race for unaligned extents\n\nAfter unaligned compressed extents were introduced, the following race\ncould occur:\n\n[Thread 1]                                   [Thread 2]\n(z_erofs_fill_bio_vec)\n\u003chandle a Z_EROFS_PREALLOCATED_FOLIO folio\u003e\n...\nfilemap_add_folio (1)\n                                             (z_erofs_bind_cache)\n                                             \u003cthe same folio is found..\u003e\n                                             ..\n                                             ..\nfolio_attach_private (2)\n                                             filemap_add_folio (3) again\n\nSince (1) is executed but (2) hasn\u0027t been executed yet, it\u0027s possible\nthat another thread finds the same managed folio in z_erofs_bind_cache()\nfor a different pcluster and calls filemap_add_folio() again since\nfolio-\u003eprivate is still Z_EROFS_PREALLOCATED_FOLIO.\n\nFix this by explicitly clearing folio-\u003eprivate before making the folio\nvisible in the managed cache so that another pcluster can simply wait\non the locked managed folio as what we did for other shared cases [1].\n\nThis only impacts unaligned data compression (`-E48bit` with zstd,\nfor example).\n\n[1] Commit 9e2f9d34dd12 (\"erofs: handle overlapped pclusters out of\n crafted images properly\") was originally introduced to handle crafted\n overlapped extents, but it addresses unaligned extents as well."
        }
      ],
      "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 only through local VFS read paths (`read`/`pread`/`mmap` faults) on a mounted EROFS volume, flowing through `z_erofs_read_folio`/`z_erofs_readahead` \u2192 `z_erofs_runqueue` \u2192 `z_erofs_submit_queue` \u2192 `z_erofs_fill_bio_vec` and `z_erofs_bind_cache`. There is no network-facing handler; exploitation requires local filesystem access.\nAC:L - The race is between concurrent read/decompress threads that the attacker fully controls by issuing parallel reads against a crafted image with overlapping unaligned compressed extents. No timing or layout conditions outside attacker control are required beyond crafting the image and spawning concurrent I/O.\nPR:L - Triggering the vulnerable managed-cache path requires mounting a crafted EROFS image with unaligned zstd extents, which is achievable with CAP_SYS_ADMIN inside an unprivileged user namespace (`unshare -Urn`) plus loop mount. After mount, only normal unprivileged file read access is needed to hit the race.\nUI:N - Once the attacker can mount the crafted image (e.g., via user namespace), exploitation is fully automated through concurrent reads and requires no additional victim interaction such as opening a specific application or clicking a link.\nS:U - Impact is confined to kernel memory corruption and privilege escalation within the same kernel/host security boundary; this is not a VM escape, IOMMU bypass, or cross-authority sandbox breakout.\nC:H - The race leaves managed folios visible in the page cache while `folio-\u003eprivate` still marks them preallocated, allowing duplicate `filemap_add_folio` and conflicting `folio_attach_private`/`folio_detach_private` bindings to different pclusters\u2014classic page-cache corruption that can yield arbitrary kernel memory disclosure via confused folio ownership.\nI:H - Associating one managed folio with multiple pclusters corrupts `folio-\u003eprivate` and compressed-bvec references, creating use-after-free/refcount confusion in the managed cache that is exploitable for arbitrary kernel writes or control-flow hijack, not merely a benign error return.\nA:H - The corrupted managed-cache state can cause kernel oops/panic, hung tasks, or deadlock (similar overlapped-pcluster crafted-image failures previously caused syzbot hangs), and any successful UAF in this path also implies high availability impact even before full exploitation."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:38:25.282Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/425d32d6288d7d845e486af9419bbedccd8c9103"
        },
        {
          "url": "https://git.kernel.org/stable/c/038166f873c4caf6e85cfd4ea0c5a5ba297b4e8b"
        },
        {
          "url": "https://git.kernel.org/stable/c/649932fc3815eda2f24eb4de4b3a5e94886ee0b9"
        }
      ],
      "title": "erofs: fix managed cache race for unaligned extents",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64031",
    "datePublished": "2026-07-19T15:39:21.609Z",
    "dateReserved": "2026-07-19T07:54:57.028Z",
    "dateUpdated": "2026-08-05T12:38:25.282Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-64031",
      "date": "2026-09-04",
      "epss": "0.00127",
      "percentile": "0.02663"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-64031\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-07-19T16:17:43.250\",\"lastModified\":\"2026-07-30T14:59:47.950\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nerofs: fix managed cache race for unaligned extents\\n\\nAfter unaligned compressed extents were introduced, the following race\\ncould occur:\\n\\n[Thread 1]                                   [Thread 2]\\n(z_erofs_fill_bio_vec)\\n\u003chandle a Z_EROFS_PREALLOCATED_FOLIO folio\u003e\\n...\\nfilemap_add_folio (1)\\n                                             (z_erofs_bind_cache)\\n                                             \u003cthe same folio is found..\u003e\\n                                             ..\\n                                             ..\\nfolio_attach_private (2)\\n                                             filemap_add_folio (3) again\\n\\nSince (1) is executed but (2) hasn\u0027t been executed yet, it\u0027s possible\\nthat another thread finds the same managed folio in z_erofs_bind_cache()\\nfor a different pcluster and calls filemap_add_folio() again since\\nfolio-\u003eprivate is still Z_EROFS_PREALLOCATED_FOLIO.\\n\\nFix this by explicitly clearing folio-\u003eprivate before making the folio\\nvisible in the managed cache so that another pcluster can simply wait\\non the locked managed folio as what we did for other shared cases [1].\\n\\nThis only impacts unaligned data compression (`-E48bit` with zstd,\\nfor example).\\n\\n[1] Commit 9e2f9d34dd12 (\\\"erofs: handle overlapped pclusters out of\\n crafted images properly\\\") was originally introduced to handle crafted\\n overlapped extents, but it addresses unaligned extents as well.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/erofs/zdata.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"7361d1e3763baaf7b9349c576137851458ad38d1\",\"lessThan\":\"425d32d6288d7d845e486af9419bbedccd8c9103\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"7361d1e3763baaf7b9349c576137851458ad38d1\",\"lessThan\":\"038166f873c4caf6e85cfd4ea0c5a5ba297b4e8b\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"7361d1e3763baaf7b9349c576137851458ad38d1\",\"lessThan\":\"649932fc3815eda2f24eb4de4b3a5e94886ee0b9\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"fs/erofs/zdata.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.15\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.15\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.34\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.0.11\",\"lessThanOrEqual\":\"7.0.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":7.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":5.9}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/038166f873c4caf6e85cfd4ea0c5a5ba297b4e8b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/425d32d6288d7d845e486af9419bbedccd8c9103\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/649932fc3815eda2f24eb4de4b3a5e94886ee0b9\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "None",
      "current_release_date": "2026-08-05T14:21:24+00:00",
      "cve": "CVE-2026-64031",
      "id": "CVE-2026-64031",
      "initial_release_date": "2026-07-19T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: erofs: fix managed cache race for unaligned extents",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64031.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.