GHSA-WCF3-P4HX-GG65

Vulnerability from github – Published: 2026-09-25 12:31 – Updated: 2026-10-22 18:38
VLAI
Details

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

smb/client: invalidate fscache for fallocate range operations

smb3_zero_range(), smb3_punch_hole(), smb3_insert_range(), and smb3_collapse_range() modify file contents through server-side range operations. These operations discard the affected page cache, but leave the FS-Cache cookie valid, so a later read may return data cached before the range operation.

Fix this by invalidating FS-Cache after outstanding I/O has completed and before modifying the file on the server.

Run the following as root on a CIFS mount with fsc enabled and an active CacheFiles backend:

    bash -c '
            MNT=/mnt/cifs
            FILE="$MNT/repro"

            # Generate four 1 MiB random blocks: [A][B][C][D].
            dd if=/dev/urandom of=/tmp/src bs=1M count=4 status=none

            # Expected contents after zeroing B: [A][zero][C][D].
            cp /tmp/src /tmp/expected
            dd if=/dev/zero of=/tmp/expected bs=1M seek=1 count=1 \
                    conv=notrunc status=none
            cp /tmp/src "$FILE"

            # Populate FS-Cache, then discard the page cache.
            sync
            echo 1 > /proc/sys/vm/drop_caches
            cat "$FILE" > /dev/null
            sync
            echo 1 > /proc/sys/vm/drop_caches

            fallocate --zero-range -o 1M -l 1M "$FILE"

            if cmp -s /tmp/expected "$FILE"; then
                    echo "readback: OK"
            else
                    echo "readback: STALE DATA"
            fi
    '

Before this change, the readback differs from /tmp/expected:

    readback: STALE DATA

After this change, it matches:

    readback: OK
Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Show details on source website
To clipboard 

{
  "affected": [],
  "aliases": [
    "CVE-2026-98124"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-672"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-25T11:17:43Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb/client: invalidate fscache for fallocate range operations\n\nsmb3_zero_range(), smb3_punch_hole(), smb3_insert_range(), and\nsmb3_collapse_range() modify file contents through server-side range\noperations. These operations discard the affected page cache, but leave\nthe FS-Cache cookie valid, so a later read may return data cached before\nthe range operation.\n\nFix this by invalidating FS-Cache after outstanding I/O has completed\nand before modifying the file on the server.\n\nRun the following as root on a CIFS mount with fsc enabled and an active\nCacheFiles backend:\n\n        bash -c \u0027\n                MNT=/mnt/cifs\n                FILE=\"$MNT/repro\"\n\n                # Generate four 1 MiB random blocks: [A][B][C][D].\n                dd if=/dev/urandom of=/tmp/src bs=1M count=4 status=none\n\n                # Expected contents after zeroing B: [A][zero][C][D].\n                cp /tmp/src /tmp/expected\n                dd if=/dev/zero of=/tmp/expected bs=1M seek=1 count=1 \\\n                        conv=notrunc status=none\n                cp /tmp/src \"$FILE\"\n\n                # Populate FS-Cache, then discard the page cache.\n                sync\n                echo 1 \u003e /proc/sys/vm/drop_caches\n                cat \"$FILE\" \u003e /dev/null\n                sync\n                echo 1 \u003e /proc/sys/vm/drop_caches\n\n                fallocate --zero-range -o 1M -l 1M \"$FILE\"\n\n                if cmp -s /tmp/expected \"$FILE\"; then\n                        echo \"readback: OK\"\n                else\n                        echo \"readback: STALE DATA\"\n                fi\n        \u0027\n\nBefore this change, the readback differs from /tmp/expected:\n\n        readback: STALE DATA\n\nAfter this change, it matches:\n\n        readback: OK",
  "id": "GHSA-wcf3-p4hx-gg65",
  "modified": "2026-10-22T18:38:33Z",
  "published": "2026-09-25T12:31:37Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98124"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/448ba0ae65ca61064183564d2983c9aa59bd6ba7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/93c6e5a8d7c5071d586c1411596d5db5faad22b2"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cc7202a51b8777a757bda9dcfbf339f828c6a130"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/dd8b1e808f5c19479e6ed47e2f88a1fd46f8b0e5"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.

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.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

JSON
How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

Loading timeline…




    Related by attack behaviour

    Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.