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

Vulnerability from cvelistv5 – Published: 2026-08-15 05:56 – Updated: 2026-08-17 05:43
VLAI
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
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 7b589a9b45ae32aa9d7bece597490e141198d7a6 , < 8ab75e445c161c4cb504aa98e20ce1dd1ecd8e9a (git)
Affected: 7b589a9b45ae32aa9d7bece597490e141198d7a6 , < 1188a9846fadeacf9d1430b528e5217f749d665b (git)
Affected: 7b589a9b45ae32aa9d7bece597490e141198d7a6 , < dbd6f56d975b23241b7bbb11bb8f562af548a0aa (git)
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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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{
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          "product": "Linux",
          "programFiles": [
            "fs/netfs/write_issue.c"
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          "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()."
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            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
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              "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."
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          "url": "https://git.kernel.org/stable/c/dbd6f56d975b23241b7bbb11bb8f562af548a0aa"
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    "datePublished": "2026-08-15T05:56:04.016Z",
    "dateReserved": "2026-08-09T03:40:39.922Z",
    "dateUpdated": "2026-08-17T05:43:19.861Z",
    "state": "PUBLISHED"
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  }
}



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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.


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