Vulnerability-Lookup

FKIE_CVE-2026-89630

Vulnerability from fkie_nvd - Published: 2026-09-11 20:19 - Updated: 2026-10-19 09:17

Severity

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

Summary

In the Linux kernel, the following vulnerability has been resolved: smb: client: restore the data_offset bound in is_valid_oplock_break() Commit 83bfbd0bb902 ("cifs: Remove the RFC1002 header from smb_hdr") changed the quantity this bound is measured against. It used to be srv->total_read minus the 4-byte RFC1002 preamble that total_read then included, so it was the SMB message length. The same commit stopped counting the preamble, and the mechanical substitution to srv->total_read - srv->pdu_size left an expression that is identically zero: standard_receive3() reads MID_HEADER_SIZE() bytes and then exactly pdu_length - MID_HEADER_SIZE() more, adding both to total_read. len is therefore 0, the subtraction below it wraps, and no __u32 DataOffset can exceed the result, so the check from commit 097f5863b1a0 ("cifs: read overflow in is_valid_oplock_break()") no longer rejects anything. Use total_read, which is now the message length on its own.

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/5b16a1967a01ad4496a7206a87c3eb16f1df2b05
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/ba22f575de9deeae4ae0859ca4315a7698226237

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/client/smb1misc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "5b16a1967a01ad4496a7206a87c3eb16f1df2b05",
              "status": "affected",
              "version": "83bfbd0bb9025f98fa62b44f93bd67466773d1db",
              "versionType": "git"
            },
            {
              "lessThan": "ba22f575de9deeae4ae0859ca4315a7698226237",
              "status": "affected",
              "version": "83bfbd0bb9025f98fa62b44f93bd67466773d1db",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "78e718c5aa146063cd70d2cc68297c3ac41f31ee",
              "versionType": "git"
            },
            {
              "lessThan": "6.19",
              "status": "affected",
              "version": "6.18.56",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/client/smb1misc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.19"
            },
            {
              "lessThan": "6.19",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: restore the data_offset bound in is_valid_oplock_break()\n\nCommit 83bfbd0bb902 (\"cifs: Remove the RFC1002 header from smb_hdr\")\nchanged the quantity this bound is measured against.  It used to be\nsrv-\u003etotal_read minus the 4-byte RFC1002 preamble that total_read then\nincluded, so it was the SMB message length.  The same commit stopped\ncounting the preamble, and the mechanical substitution to\nsrv-\u003etotal_read - srv-\u003epdu_size left an expression that is identically\nzero: standard_receive3() reads MID_HEADER_SIZE() bytes and then exactly\npdu_length - MID_HEADER_SIZE() more, adding both to total_read.\n\nlen is therefore 0, the subtraction below it wraps, and no __u32\nDataOffset can exceed the result, so the check from commit 097f5863b1a0\n(\"cifs: read overflow in is_valid_oplock_break()\") no longer rejects\nanything.  Use total_read, which is now the message length on its own."
    }
  ],
  "id": "CVE-2026-89630",
  "lastModified": "2026-10-19T09:17:59.930",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.1,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.2,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-09-11T20:19:48.517",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/5b16a1967a01ad4496a7206a87c3eb16f1df2b05"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ba22f575de9deeae4ae0859ca4315a7698226237"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}

CVE-2026-89630 (GCVE-0-2026-89630)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:45 – Updated: 2026-10-19 08:50

Title

smb: client: restore the data_offset bound in is_valid_oplock_break()

Summary

Severity

9.1 (Critical)


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

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 6639 records in the last 180 days details

References

2 references

URL	Tags
https://git.kernel.org/stable/c/5b16a1967a01ad449…
https://git.kernel.org/stable/c/ba22f575de9deeae4…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 83bfbd0bb9025f98fa62b44f93bd67466773d1db , < 5b16a1967a01ad4496a7206a87c3eb16f1df2b05 (git) Affected: 83bfbd0bb9025f98fa62b44f93bd67466773d1db , < ba22f575de9deeae4ae0859ca4315a7698226237 (git) Affected: 78e718c5aa146063cd70d2cc68297c3ac41f31ee (git) Affected: 6.18.56 , < 6.19 (semver)
Linux	Linux	Affected: 6.19 Unaffected: 0 , < 6.19 (semver) Unaffected: 7.2.4 , ≤ 7.2.* (semver) Unaffected: 7.3 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/client/smb1misc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "5b16a1967a01ad4496a7206a87c3eb16f1df2b05",
              "status": "affected",
              "version": "83bfbd0bb9025f98fa62b44f93bd67466773d1db",
              "versionType": "git"
            },
            {
              "lessThan": "ba22f575de9deeae4ae0859ca4315a7698226237",
              "status": "affected",
              "version": "83bfbd0bb9025f98fa62b44f93bd67466773d1db",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "78e718c5aa146063cd70d2cc68297c3ac41f31ee",
              "versionType": "git"
            },
            {
              "lessThan": "6.19",
              "status": "affected",
              "version": "6.18.56",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/client/smb1misc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.19"
            },
            {
              "lessThan": "6.19",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.4",
                  "versionStartIncluding": "6.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "6.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "6.18.56",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: restore the data_offset bound in is_valid_oplock_break()\n\nCommit 83bfbd0bb902 (\"cifs: Remove the RFC1002 header from smb_hdr\")\nchanged the quantity this bound is measured against.  It used to be\nsrv-\u003etotal_read minus the 4-byte RFC1002 preamble that total_read then\nincluded, so it was the SMB message length.  The same commit stopped\ncounting the preamble, and the mechanical substitution to\nsrv-\u003etotal_read - srv-\u003epdu_size left an expression that is identically\nzero: standard_receive3() reads MID_HEADER_SIZE() bytes and then exactly\npdu_length - MID_HEADER_SIZE() more, adding both to total_read.\n\nlen is therefore 0, the subtraction below it wraps, and no __u32\nDataOffset can exceed the result, so the check from commit 097f5863b1a0\n(\"cifs: read overflow in is_valid_oplock_break()\") no longer rejects\nanything.  Use total_read, which is now the message length on its own."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.1,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The flaw is in the in-kernel SMB1 client demultiplex path: a remote peer sends an unsolicited SMB_COM_NT_TRANSACT response over TCP/445 and cifs_demultiplex_thread() calls is_valid_oplock_break() on unmatched frames, so a malicious or compromised SMB server (or MITM) reaches it via network protocol data.\nAC:L - The attacker fully controls Command, Flags, ByteCount, and DataOffset in a single unsolicited frame; the broken bound wraps so any DataOffset is accepted and the resulting heap over-read is deterministic, with no race or condition the attacker cannot influence once the client is on the SMB1 connection.\nPR:N - A matching MID, session setup, or tree connect is not required: after negotiate, an unmatched NT_TRANSACT+RESPONSE frame is treated as an oplock/dnotify break before authentication, so the malicious server needs no credentials or privileges on the client host.\nUI:N - On a persistent SMB1 mount (cifsroot, automount, or an already-mounted legacy NAS share) the cifsd thread processes unsolicited frames after the existing connection or reconnect, so no additional victim action is required at attack time.\nS:U - The out-of-bounds/use-after-free read occurs in kernel heap used by the CIFS client on the same host kernel security authority and does not cross a VM, IOMMU, or sandbox boundary.\nC:H - Attacker-controlled DataOffset displaces file_notify_information into adjacent or freed cifs_small_rq slab objects (KASAN use-after-free read), and printing FileName with %s can walk unbounded kernel memory, so the disclosure is not limited to a few bounded bytes.\nI:N - The displaced pointer is only read (Action and FileName for a debug print); the bug does not write through that pointer or otherwise provide a kernel memory-modification or control-flow primitive.\nA:H - The KASAN-confirmed slab use-after-free and unmapped over-read run in the cifsd demultiplex thread and can oops or panic the kernel, and a malicious peer can repeat the unsolicited frame to retrigger the crash."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:50:02.437Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/5b16a1967a01ad4496a7206a87c3eb16f1df2b05"
        },
        {
          "url": "https://git.kernel.org/stable/c/ba22f575de9deeae4ae0859ca4315a7698226237"
        }
      ],
      "title": "smb: client: restore the data_offset bound in is_valid_oplock_break()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89630",
    "datePublished": "2026-09-11T19:45:25.697Z",
    "dateReserved": "2026-09-11T19:38:34.738Z",
    "dateUpdated": "2026-10-19T08:50:02.437Z",
    "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.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

Order 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.

Publication & reservation Sightings KEV catalogs Other timestamps

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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.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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.

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