Vulnerability-Lookup

GHSA-8Q2X-69CW-5M48

Vulnerability from github – Published: 2026-08-15 06:32 – Updated: 2026-08-17 06:33

Details

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

netfs: Fix netfs_create_write_req() to handle async cache object creation

netfs_create_write_req() will skip caching if the fscache cookie is disabled, but this is a problem because async cache object creation might not have got far enough yet that has been enabled - thereby causing the call to fscache_begin_write_operation() to be skipped.

Fix this by removing the checks on the cookie and delegating this to fscache_begin_write_operation().

Severity

9.8 (Critical)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-72366"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-15T06:22:10Z",
    "severity": "CRITICAL"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfs: Fix netfs_create_write_req() to handle async cache object creation\n\nnetfs_create_write_req() will skip caching if the fscache cookie is\ndisabled, but this is a problem because async cache object creation might\nnot have got far enough yet that has been enabled - thereby causing the\ncall to fscache_begin_write_operation() to be skipped.\n\nFix this by removing the checks on the cookie and delegating this to\nfscache_begin_write_operation().",
  "id": "GHSA-8q2x-69cw-5m48",
  "modified": "2026-08-17T06:33:25Z",
  "published": "2026-08-15T06:32:21Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72366"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1188a9846fadeacf9d1430b528e5217f749d665b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8ab75e445c161c4cb504aa98e20ce1dd1ecd8e9a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/dbd6f56d975b23241b7bbb11bb8f562af548a0aa"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-72366 (GCVE-0-2026-72366)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:56 – Updated: 2026-08-17 05:43

Title

netfs: Fix netfs_create_write_req() to handle async cache object creation

Summary

In the Linux kernel, the following vulnerability has been resolved: netfs: Fix netfs_create_write_req() to handle async cache object creation netfs_create_write_req() will skip caching if the fscache cookie is disabled, but this is a problem because async cache object creation might not have got far enough yet that has been enabled - thereby causing the call to fscache_begin_write_operation() to be skipped. Fix this by removing the checks on the cookie and delegating this to fscache_begin_write_operation().

Severity

9.8 (Critical)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux mitre root

References

3 references

URL	Tags
https://git.kernel.org/stable/c/8ab75e445c161c4cb…
https://git.kernel.org/stable/c/1188a9846fadeacf9…
https://git.kernel.org/stable/c/dbd6f56d975b23241…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 7b589a9b45ae32aa9d7bece597490e141198d7a6 , < 8ab75e445c161c4cb504aa98e20ce1dd1ecd8e9a (git) Affected: 7b589a9b45ae32aa9d7bece597490e141198d7a6 , < 1188a9846fadeacf9d1430b528e5217f749d665b (git) Affected: 7b589a9b45ae32aa9d7bece597490e141198d7a6 , < dbd6f56d975b23241b7bbb11bb8f562af548a0aa (git)
Linux	Linux	Affected: 6.11 Unaffected: 0 , < 6.11 (semver) Unaffected: 6.18.40 , ≤ 6.18.* (semver) Unaffected: 7.1.5 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/netfs/write_issue.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "8ab75e445c161c4cb504aa98e20ce1dd1ecd8e9a",
              "status": "affected",
              "version": "7b589a9b45ae32aa9d7bece597490e141198d7a6",
              "versionType": "git"
            },
            {
              "lessThan": "1188a9846fadeacf9d1430b528e5217f749d665b",
              "status": "affected",
              "version": "7b589a9b45ae32aa9d7bece597490e141198d7a6",
              "versionType": "git"
            },
            {
              "lessThan": "dbd6f56d975b23241b7bbb11bb8f562af548a0aa",
              "status": "affected",
              "version": "7b589a9b45ae32aa9d7bece597490e141198d7a6",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/netfs/write_issue.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.11"
            },
            {
              "lessThan": "6.11",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.40",
              "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": "6.18.40",
                  "versionStartIncluding": "6.11",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.5",
                  "versionStartIncluding": "6.11",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "6.11",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfs: Fix netfs_create_write_req() to handle async cache object creation\n\nnetfs_create_write_req() will skip caching if the fscache cookie is\ndisabled, but this is a problem because async cache object creation might\nnot have got far enough yet that has been enabled - thereby causing the\ncall to fscache_begin_write_operation() to be skipped.\n\nFix this by removing the checks on the cookie and delegating this to\nfscache_begin_write_operation()."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The bug is in netfs client write/cache coordination for CIFS, NFS+fscache, Ceph, AFS, and 9p. A malicious remote filesystem server can deliver file data and control protocol timing to drive async fscache object creation and subsequent kernel writeback over the network.\nAC:L - The attacker controls both sides of the race by interleaving reads and writes or triggering writeback while the fscache cookie is still in CREATING/LOOKING_UP; the async-creation window can be hit reliably with retries, not conditions outside attacker influence.\nPR:N - A malicious NFS/SMB/Ceph server needs no privileges on the victim client; once a fscache-enabled mount to that server exists, exploitation requires only ordinary file access or automated writeback, not real root or init-namespace capabilities.\nUI:N - After a triggering read from the remote server, kernel writeback can invoke netfs_writepages without further victim action; an attacker with file access can also drive the race directly through concurrent read/write syscalls.\nS:U - Impact is kernel heap/folio corruption during local pagecache I/O within the same kernel security authority; it does not inherently cross VM, container, IOMMU, or sandbox boundaries.\nC:H - Skipping fscache_begin_write_operation desynchronizes cache and writeback streams; the same netfs/fscache subsystem previously produced UAFs when PG_private_2 coordination failed, enabling disclosure via freed/reused folio memory.\nI:H - Inconsistent dual-stream write completion can free or reuse folios while still referenced, yielding heap corruption primitives that related netfs fscache bugs have leveraged for arbitrary kernel writes and privilege escalation.\nA:H - The related netfs fscache fix documented kernel oops, ceph caps warnings, RCU expedited stalls, and UAF crashes from this coordination failure class; skipping required cache setup can oops, panic, or hang the system during writeback."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:43:19.861Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/8ab75e445c161c4cb504aa98e20ce1dd1ecd8e9a"
        },
        {
          "url": "https://git.kernel.org/stable/c/1188a9846fadeacf9d1430b528e5217f749d665b"
        },
        {
          "url": "https://git.kernel.org/stable/c/dbd6f56d975b23241b7bbb11bb8f562af548a0aa"
        }
      ],
      "title": "netfs: Fix netfs_create_write_req() to handle async cache object creation",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-72366",
    "datePublished": "2026-08-15T05:56:04.016Z",
    "dateReserved": "2026-08-09T03:40:39.922Z",
    "dateUpdated": "2026-08-17T05:43:19.861Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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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.

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.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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GHSA-8Q2X-69CW-5M48

CVE-2026-72366 (GCVE-0-2026-72366)

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