Vulnerability-Lookup

FKIE_CVE-2026-43185

Vulnerability from fkie_nvd - Published: 2026-05-06 12:16 - Updated: 2026-06-17 10:49

Severity

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

Summary

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix signededness bug in smb_direct_prepare_negotiation() smb_direct_prepare_negotiation() casts an unsigned __u32 value from sp->max_recv_size and req->preferred_send_size to a signed int before computing min_t(int, ...). A maliciously provided preferred_send_size of 0x80000000 will return as smaller than max_recv_size, and then be used to set the maximum allowed alowed receive size for the next message. By sending a second message with a large value (>1420 bytes) the attacker can then achieve a heap buffer overflow. This fix replaces min_t(int, ...) with min_t(u32)

References

URL	Tags
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/55abc475d096da4a5356b6efb0cfdc6156bc1550	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/6b4f875aac344cdd52a1f34cc70ed2f874a65757	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/ceae058eb707ddd0d68f0872f9d9f23b7c30c37b	Patch

Impacted products

Vendor	Product	Version
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	7.0

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/transport_rdma.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "ceae058eb707ddd0d68f0872f9d9f23b7c30c37b",
              "status": "affected",
              "version": "0626e6641f6b467447c81dd7678a69c66f7746cf",
              "versionType": "git"
            },
            {
              "lessThan": "55abc475d096da4a5356b6efb0cfdc6156bc1550",
              "status": "affected",
              "version": "0626e6641f6b467447c81dd7678a69c66f7746cf",
              "versionType": "git"
            },
            {
              "lessThan": "6b4f875aac344cdd52a1f34cc70ed2f874a65757",
              "status": "affected",
              "version": "0626e6641f6b467447c81dd7678a69c66f7746cf",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/transport_rdma.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.15"
            },
            {
              "lessThan": "5.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.16",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
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              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "E3B207F9-B76D-4B19-8860-9E40E6B32274",
              "versionEndExcluding": "6.18.16",
              "versionStartIncluding": "5.15",
              "vulnerable": true
            },
            {
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              "matchCriteriaId": "373EEEDA-FAA1-4FB4-B6ED-DB4DD99DBE67",
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            },
            {
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              "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16",
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  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix signededness bug in smb_direct_prepare_negotiation()\n\nsmb_direct_prepare_negotiation() casts an unsigned __u32 value\nfrom sp-\u003emax_recv_size and req-\u003epreferred_send_size to a signed\nint before computing min_t(int, ...). A maliciously provided\npreferred_send_size of 0x80000000 will return as smaller than\nmax_recv_size, and then be used to set the maximum allowed\nalowed receive size for the next message.\n\nBy sending a second message with a large value (\u003e1420 bytes)\nthe attacker can then achieve a heap buffer overflow.\n\nThis fix replaces min_t(int, ...) with min_t(u32)"
    }
  ],
  "id": "CVE-2026-43185",
  "lastModified": "2026-06-17T10:49:06.787",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.8,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-05-06T12:16:37.187",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/55abc475d096da4a5356b6efb0cfdc6156bc1550"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/6b4f875aac344cdd52a1f34cc70ed2f874a65757"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/ceae058eb707ddd0d68f0872f9d9f23b7c30c37b"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-674"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}

CVE-2026-43185 (GCVE-0-2026-43185)

Vulnerability from cvelistv5 – Published: 2026-05-06 11:27 – Updated: 2026-08-05 12:26

Title

ksmbd: fix signededness bug in smb_direct_prepare_negotiation()

Summary

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/ceae058eb707ddd0d…
https://git.kernel.org/stable/c/55abc475d096da4a5…
https://git.kernel.org/stable/c/6b4f875aac344cdd5…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 0626e6641f6b467447c81dd7678a69c66f7746cf , < ceae058eb707ddd0d68f0872f9d9f23b7c30c37b (git) Affected: 0626e6641f6b467447c81dd7678a69c66f7746cf , < 55abc475d096da4a5356b6efb0cfdc6156bc1550 (git) Affected: 0626e6641f6b467447c81dd7678a69c66f7746cf , < 6b4f875aac344cdd52a1f34cc70ed2f874a65757 (git)
Linux	Linux	Affected: 5.15 Unaffected: 0 , < 5.15 (semver) Unaffected: 6.18.16 , ≤ 6.18.* (semver) Unaffected: 6.19.6 , ≤ 6.19.* (semver) Unaffected: 7.0 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/transport_rdma.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "ceae058eb707ddd0d68f0872f9d9f23b7c30c37b",
              "status": "affected",
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              "versionType": "git"
            },
            {
              "lessThan": "55abc475d096da4a5356b6efb0cfdc6156bc1550",
              "status": "affected",
              "version": "0626e6641f6b467447c81dd7678a69c66f7746cf",
              "versionType": "git"
            },
            {
              "lessThan": "6b4f875aac344cdd52a1f34cc70ed2f874a65757",
              "status": "affected",
              "version": "0626e6641f6b467447c81dd7678a69c66f7746cf",
              "versionType": "git"
            }
          ]
        },
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          "product": "Linux",
          "programFiles": [
            "fs/smb/server/transport_rdma.c"
          ],
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          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.15"
            },
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              "lessThan": "5.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
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              "status": "unaffected",
              "version": "6.18.16",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix signededness bug in smb_direct_prepare_negotiation()\n\nsmb_direct_prepare_negotiation() casts an unsigned __u32 value\nfrom sp-\u003emax_recv_size and req-\u003epreferred_send_size to a signed\nint before computing min_t(int, ...). A maliciously provided\npreferred_send_size of 0x80000000 will return as smaller than\nmax_recv_size, and then be used to set the maximum allowed\nalowed receive size for the next message.\n\nBy sending a second message with a large value (\u003e1420 bytes)\nthe attacker can then achieve a heap buffer overflow.\n\nThis fix replaces min_t(int, ...) with min_t(u32)"
        }
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          },
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            {
              "lang": "en",
              "value": "AV:N - The vulnerable ksmbd SMB Direct negotiation is reached by a remote peer over the network via the RDMA listener on SMB Direct ports such as 445/5445.\nAC:L - An attacker can trigger the bug with a crafted negotiation request followed by an oversized data-transfer message; no race or victim-controlled timing is required.\nPR:N - The vulnerable path runs during SMB Direct transport negotiation before SMB authentication or session setup, so no credentials or prior privileges are required.\nUI:N - No victim user action is needed beyond the server exposing ksmbd SMB Direct; the attacker sends network protocol messages directly.\nS:U - The impact is kernel memory corruption within the same host security authority, not a cross-scope escape such as guest-to-host or IOMMU boundary bypass.\nC:H - The signedness bug lets the attacker turn a small allocated receive buffer into a huge posted RDMA receive target, causing attacker-controlled kernel heap memory corruption that can plausibly be leveraged for information disclosure.\nI:H - The second SMB Direct message causes an out-of-bounds write/DMA overwrite into kernel heap memory, which is high-integrity impact and plausibly exploitable for control-flow or data corruption.\nA:H - The heap buffer overflow is remotely triggerable pre-authentication and can crash or panic the kernel even without full code execution."
            }
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    "dateReserved": "2026-05-01T14:12:55.991Z",
    "dateUpdated": "2026-08-05T12:26:23.248Z",
    "state": "PUBLISHED"
  },
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}

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.
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.