Vulnerability-Lookup

FKIE_CVE-2026-89632

Vulnerability from fkie_nvd - Published: 2026-09-11 20:19 - Updated: 2026-09-13 07:17

Severity

8.2 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H

Summary

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix use-before-check of ReparseDataLength in reparse_buf_ptr() reparse_buf_ptr() reads buf->ReparseDataLength before checking that count covers the full fixed header: buf = (struct reparse_data_buffer *)((u8 *)io + off); len = sizeof(*buf); /* 8 bytes */ rdlen = le16_to_cpu(buf->ReparseDataLength); /* offset 4, 2 bytes */ if (count < len || count < rdlen + len) /* check comes after */ struct reparse_data_buffer has ReparseDataLength at offset 4. If a server returns OutputCount < 6, the read at offset 4-5 reaches past the end of the received data. The off+count bounds against iov_len were already validated, but that does not protect against count being smaller than sizeof(*buf). Split the check: verify count >= sizeof(*buf) before reading ReparseDataLength, then verify count covers the data region.

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/05f78e6cf34ea3a285053bd5999e08e8ac298bd5
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/711cf71300d7992f450600df8864917d3538679f

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/client/smb2inode.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "711cf71300d7992f450600df8864917d3538679f",
              "status": "affected",
              "version": "a158bb66b1373866d9fd5997565a58a573085539",
              "versionType": "git"
            },
            {
              "lessThan": "05f78e6cf34ea3a285053bd5999e08e8ac298bd5",
              "status": "affected",
              "version": "a158bb66b1373866d9fd5997565a58a573085539",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/client/smb2inode.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "7.2.4",
              "status": "affected",
              "version": "6.6.32",
              "versionType": "semver"
            },
            {
              "lessThan": "7.3-rc1",
              "status": "affected",
              "version": "6.6.32",
              "versionType": "semver"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix use-before-check of ReparseDataLength in reparse_buf_ptr()\n\nreparse_buf_ptr() reads buf-\u003eReparseDataLength before checking that\ncount covers the full fixed header:\n\n    buf = (struct reparse_data_buffer *)((u8 *)io + off);\n    len = sizeof(*buf);                          /* 8 bytes */\n    rdlen = le16_to_cpu(buf-\u003eReparseDataLength); /* offset 4, 2 bytes */\n\n    if (count \u003c len || count \u003c rdlen + len)      /* check comes after */\n\nstruct reparse_data_buffer has ReparseDataLength at offset 4.  If a\nserver returns OutputCount \u003c 6, the read at offset 4-5 reaches past\nthe end of the received data.  The off+count bounds against iov_len\nwere already validated, but that does not protect against count being\nsmaller than sizeof(*buf).\n\nSplit the check: verify count \u003e= sizeof(*buf) before reading\nReparseDataLength, then verify count covers the data region."
    }
  ],
  "id": "CVE-2026-89632",
  "lastModified": "2026-09-13T07:17:28.300",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 8.2,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "LOW",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 4.2,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-09-11T20:19:48.763",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/05f78e6cf34ea3a285053bd5999e08e8ac298bd5"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/711cf71300d7992f450600df8864917d3538679f"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}

CVE-2026-89632 (GCVE-0-2026-89632)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:45 – Updated: 2026-09-13 06:32

Title

smb: client: fix use-before-check of ReparseDataLength in reparse_buf_ptr()

Summary

Severity

8.2 (High)


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

Assigner

Linux mitre root

References

2 references

URL	Tags
https://git.kernel.org/stable/c/711cf71300d7992f4…
https://git.kernel.org/stable/c/05f78e6cf34ea3a28…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: a158bb66b1373866d9fd5997565a58a573085539 , < 711cf71300d7992f450600df8864917d3538679f (git) Affected: a158bb66b1373866d9fd5997565a58a573085539 , < 05f78e6cf34ea3a285053bd5999e08e8ac298bd5 (git)
Linux	Linux	Affected: 6.6.32 , < 7.2.4 (semver) Affected: 6.6.32 , < 7.3-rc1 (semver)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/client/smb2inode.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "711cf71300d7992f450600df8864917d3538679f",
              "status": "affected",
              "version": "a158bb66b1373866d9fd5997565a58a573085539",
              "versionType": "git"
            },
            {
              "lessThan": "05f78e6cf34ea3a285053bd5999e08e8ac298bd5",
              "status": "affected",
              "version": "a158bb66b1373866d9fd5997565a58a573085539",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/client/smb2inode.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "7.2.4",
              "status": "affected",
              "version": "6.6.32",
              "versionType": "semver"
            },
            {
              "lessThan": "7.3-rc1",
              "status": "affected",
              "version": "6.6.32",
              "versionType": "semver"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.4",
                  "versionStartIncluding": "6.6.32",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc1",
                  "versionStartIncluding": "6.6.32",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix use-before-check of ReparseDataLength in reparse_buf_ptr()\n\nreparse_buf_ptr() reads buf-\u003eReparseDataLength before checking that\ncount covers the full fixed header:\n\n    buf = (struct reparse_data_buffer *)((u8 *)io + off);\n    len = sizeof(*buf);                          /* 8 bytes */\n    rdlen = le16_to_cpu(buf-\u003eReparseDataLength); /* offset 4, 2 bytes */\n\n    if (count \u003c len || count \u003c rdlen + len)      /* check comes after */\n\nstruct reparse_data_buffer has ReparseDataLength at offset 4.  If a\nserver returns OutputCount \u003c 6, the read at offset 4-5 reaches past\nthe end of the received data.  The off+count bounds against iov_len\nwere already validated, but that does not protect against count being\nsmaller than sizeof(*buf).\n\nSplit the check: verify count \u003e= sizeof(*buf) before reading\nReparseDataLength, then verify count covers the data region."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.2,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The flaw is in the in-kernel SMB client parser for FSCTL_GET_REPARSE_POINT IOCTL replies on TCP/445. A malicious, compromised, or on-path SMB server reaches reparse_buf_ptr() with crafted OutputOffset/OutputCount; this matches sibling client response-parsing scores such as CVE-2026-46155 and CVE-2024-49996.\nAC:L - The server fully controls OutputOffset and OutputCount. A successful IOCTL PDU with OutputCount \u003c 6 and OutputOffset near iov_len (for example a 448-byte cifs_small_rq-sized frame) deterministically loads ReparseDataLength past the received payload, with no race or attacker-uncontrollable layout.\nPR:N - The attacker is the remote SMB server (or a MITM on an unsigned session) and needs no account, credentials, or capabilities on the victim client. GET_REPARSE runs on an already established tree connect after ordinary CREATE/lookup; the client authenticates to the server, not the reverse.\nUI:N - On an already-mounted or automounted CIFS share, any routine lookup/stat of a reparse point \u2014 including files the server flags as reparse in CREATE \u2014 issues FSCTL_GET_REPARSE_POINT. Backup jobs, indexers, and inode revalidation hit the parser with no contemporaneous victim mount action.\nS:U - The two-byte out-of-bounds load and any resulting oops stay inside the client kernel\u0027s security authority. The bug does not cross a VM, IOMMU, or sandbox boundary.\nC:L - The use-before-check reads exactly two bytes of ReparseDataLength past the IOCTL output region (and, when the PDU fills cifs_small_rq, past that 448-byte slab). Those bytes are passed only to smb_EIO2 tracing, so disclosure is strictly bounded, matching CVE-2026-64448 rather than unbounded heap leaks.\nI:N - The out-of-bounds access is a u16 load used only in the subsequent length check and error trace. On failure the helper returns -EIO and does not install a reparse tag or copy payload, so there is no kernel write or metadata-corruption primitive.\nA:H - A PDU that fills the cifs_small_rq or cifs_request slab with OutputOffset at the object end makes the two-byte load a true slab-out-of-bounds access, which KASAN reports as a BUG and which can oops/panic if the next page is unmapped. A malicious server can retrigger it on every GET_REPARSE."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-13T06:32:11.058Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/711cf71300d7992f450600df8864917d3538679f"
        },
        {
          "url": "https://git.kernel.org/stable/c/05f78e6cf34ea3a285053bd5999e08e8ac298bd5"
        }
      ],
      "title": "smb: client: fix use-before-check of ReparseDataLength in reparse_buf_ptr()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89632",
    "datePublished": "2026-09-11T19:45:27.325Z",
    "dateReserved": "2026-09-11T19:38:34.738Z",
    "dateUpdated": "2026-09-13T06:32:11.058Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

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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