Vulnerability-Lookup

CVE-2026-99083 (GCVE-0-2026-99083)

Vulnerability from cvelistv5 – Published: 2026-10-23 12:45 – Updated: 2026-10-26 06:56

Title

ksmbd: fix heap out-of-bounds write in krb5_authenticate()

Summary

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix heap out-of-bounds write in krb5_authenticate() In krb5_authenticate(), out_len is calculated to determine available headroom in response_buf for the incoming Kerberos AP-REP token. However, when SMB2_SESSION_SETUP is processed as a non-first element of a compounded SMB2 request, the calculation omits work->next_smb2_rsp_hdr_off. This causes out_len to overstate remaining buffer headroom by the cumulative size of prior responses in the compound chain. Consequently, the length check in ksmbd_krb5_authenticate() (*out_len <= resp->spnego_blob_len) passes erroneously, allowing memcpy() to write the AP-REP blob past the end of response_buf into adjacent kernel heap memory. Fix this by subtracting work->next_smb2_rsp_hdr_off when computing out_len, ensuring it accurately reflects physical remaining buffer space.

Severity

8.8 (High)


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

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 7067 records in the last 180 days details

References

5 references

URL	Tags
https://git.kernel.org/stable/c/59c6dcc5dd9dafe76…
https://git.kernel.org/stable/c/80af1bde97d5a85ad…
https://git.kernel.org/stable/c/517404e157395d0f8…
https://git.kernel.org/stable/c/4722d06b290758507…
https://git.kernel.org/stable/c/23a0be6a84a38ac16…

Impacted products

2 products

Vendor	Product	Version	CPE status
Linux	Linux	Affected: 98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8 , < 59c6dcc5dd9dafe764ca0d40525933b2be69b059 (git) Affected: 98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8 , < 80af1bde97d5a85ad6f2c40ca894ccc8fa75a27a (git) Affected: 98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8 , < 517404e157395d0f8da125ca956c566895dfcd06 (git) Affected: 98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8 , < 4722d06b2907585074252061b1024a696c1cfc23 (git) Affected: 98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8 , < 23a0be6a84a38ac169eeab49017934e8e27c65f0 (git) Affected: 676392184785ace61e939831e7ca44a03d438c3b (git) Affected: ef572ffa8eb44111eed2925fbb2adca78bdcbf61 (git) Affected: 2ba03cecb12ac7ac9e0170e251543c56832d9959 (git) Affected: 5.15.145 , < 5.16 (semver) Affected: 6.1.40 , < 6.2 (semver) Affected: 6.4.5 , < 6.5 (semver)	guessed
Linux	Linux	Affected: 6.5 Unaffected: 0 , < 6.5 (semver) Unaffected: 6.6.160 , ≤ 6.6.* (semver) Unaffected: 6.12.114 , ≤ 6.12.* (semver) Unaffected: 6.18.58 , ≤ 6.18.* (semver) Unaffected: 7.2.12 , ≤ 7.2.* (semver) Unaffected: 7.3 , ≤ * (original_commit_for_fix)	guessed

Show details on NVD website

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/smb2pdu.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "59c6dcc5dd9dafe764ca0d40525933b2be69b059",
              "status": "affected",
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              "versionType": "git"
            },
            {
              "lessThan": "80af1bde97d5a85ad6f2c40ca894ccc8fa75a27a",
              "status": "affected",
              "version": "98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8",
              "versionType": "git"
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            {
              "lessThan": "517404e157395d0f8da125ca956c566895dfcd06",
              "status": "affected",
              "version": "98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8",
              "versionType": "git"
            },
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              "status": "affected",
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              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "ef572ffa8eb44111eed2925fbb2adca78bdcbf61",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "2ba03cecb12ac7ac9e0170e251543c56832d9959",
              "versionType": "git"
            },
            {
              "lessThan": "5.16",
              "status": "affected",
              "version": "5.15.145",
              "versionType": "semver"
            },
            {
              "lessThan": "6.2",
              "status": "affected",
              "version": "6.1.40",
              "versionType": "semver"
            },
            {
              "lessThan": "6.5",
              "status": "affected",
              "version": "6.4.5",
              "versionType": "semver"
            }
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            "fs/smb/server/smb2pdu.c"
          ],
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          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.5"
            },
            {
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.160",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.114",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.58",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.12",
              "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": "6.6.160",
                  "versionStartIncluding": "6.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.114",
                  "versionStartIncluding": "6.5",
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                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                {
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                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "6.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "5.15.145",
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                  "versionStartIncluding": "6.4.5",
                  "vulnerable": true
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              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix heap out-of-bounds write in krb5_authenticate()\n\nIn krb5_authenticate(), out_len is calculated to determine available\nheadroom in response_buf for the incoming Kerberos AP-REP token. However,\nwhen SMB2_SESSION_SETUP is processed as a non-first element of a compounded\nSMB2 request, the calculation omits work-\u003enext_smb2_rsp_hdr_off.\n\nThis causes out_len to overstate remaining buffer headroom by\nthe cumulative size of prior responses in the compound chain. Consequently,\nthe length check in ksmbd_krb5_authenticate()\n(*out_len \u003c= resp-\u003espnego_blob_len) passes erroneously, allowing memcpy()\nto write the AP-REP blob past the end of response_buf into adjacent kernel\nheap memory.\n\nFix this by subtracting work-\u003enext_smb2_rsp_hdr_off when computing out_len,\nensuring it accurately reflects physical remaining buffer space."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - ksmbd_conn_handler_loop() receives the compound request over TCP/445, and __process_request() dispatches its non-first SMB2 SESSION_SETUP to smb2_sess_setup() and krb5_authenticate(). The SESSION_SETUP SecurityBuffer carries the Kerberos AP-REQ that produces the AP-REP copied by the patched path.\nAC:L - The same authenticated peer can create directory entries, request a sized QUERY_DIRECTORY response, and place SESSION_SETUP later in the compound, controlling next_smb2_rsp_hdr_off before supplying its valid AP-REQ; no race or external actor is required.\nPR:L - ksmbd_krb5_authenticate() checks KSMBD_USER_FLAG_OK before its length check and memcpy; ksmbd.mountd sets it only after krb5_rd_req() accepts the AP-REQ and usm_handle_login_request() recognizes the account. An ordinary valid Kerberos account suffices, but an unauthenticated peer cannot reach the write.\nUI:N - The peer opens the session, prepares the prior compound response, and sends the Kerberos SESSION_SETUP itself; no victim user must open, mount, or approve anything.\nS:U - ksmbd_krb5_authenticate() corrupts memory adjacent to the host kernel\u0027s response_buf allocation; this remains within the same kernel security authority and crosses no VM, IOMMU, or sandbox boundary.\nC:H - The AP-REP memcpy in ksmbd_krb5_authenticate() can overrun response_buf and corrupt adjacent heap objects; exploitable kernel heap corruption can be converted into a memory-read primitive exposing arbitrary kernel data.\nI:H - The memcpy writes resp-\u003espnego_blob_len AP-REP bytes beyond response_buf into adjacent kernel heap memory, enabling corruption of object metadata or control data and potential kernel code execution.\nA:H - Writing the AP-REP beyond response_buf can corrupt adjacent allocations or allocator metadata and trigger KASAN, an oops, or a kernel panic; the authenticated SMB peer can repeat the compound request."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-26T06:56:58.783Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/59c6dcc5dd9dafe764ca0d40525933b2be69b059"
        },
        {
          "url": "https://git.kernel.org/stable/c/80af1bde97d5a85ad6f2c40ca894ccc8fa75a27a"
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        {
          "url": "https://git.kernel.org/stable/c/517404e157395d0f8da125ca956c566895dfcd06"
        },
        {
          "url": "https://git.kernel.org/stable/c/4722d06b2907585074252061b1024a696c1cfc23"
        },
        {
          "url": "https://git.kernel.org/stable/c/23a0be6a84a38ac169eeab49017934e8e27c65f0"
        }
      ],
      "title": "ksmbd: fix heap out-of-bounds write in krb5_authenticate()",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-99083",
    "datePublished": "2026-10-23T12:45:01.735Z",
    "dateReserved": "2026-09-25T10:25:14.390Z",
    "dateUpdated": "2026-10-26T06:56:58.783Z",
    "state": "PUBLISHED"
  },
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      "cve": "CVE-2026-99083",
      "date": "2026-10-26",
      "epss": "0.00408",
      "percentile": "0.34813"
    },
    "microsoft_vex": {
      "current_release_date": "2026-10-25T01:06:56.000Z",
      "cve": "CVE-2026-99083",
      "id": "msrc_CVE-2026-99083",
      "initial_release_date": "2026-10-25T01:05:28.000Z",
      "product_status:under_investigation": "2",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "ksmbd: fix heap out-of-bounds write in krb5_authenticate()",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-99083.json",
      "version": "2"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "defaultStatus": "unaffected",
                "product": "Linux",
                "programFiles": [
                  "fs/smb/server/smb2pdu.c"
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                    "versionType": "git"
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                  {
                    "status": "affected",
                    "version": "676392184785ace61e939831e7ca44a03d438c3b",
                    "versionType": "git"
                  },
                  {
                    "status": "affected",
                    "version": "ef572ffa8eb44111eed2925fbb2adca78bdcbf61",
                    "versionType": "git"
                  },
                  {
                    "status": "affected",
                    "version": "2ba03cecb12ac7ac9e0170e251543c56832d9959",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "5.16",
                    "status": "affected",
                    "version": "5.15.145",
                    "versionType": "semver"
                  },
                  {
                    "lessThan": "6.2",
                    "status": "affected",
                    "version": "6.1.40",
                    "versionType": "semver"
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                  {
                    "lessThan": "6.5",
                    "status": "affected",
                    "version": "6.4.5",
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              },
              {
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                "product": "Linux",
                "programFiles": [
                  "fs/smb/server/smb2pdu.c"
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                "vendor": "Linux",
                "versions": [
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                    "version": "6.12.114",
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                    "status": "unaffected",
                    "version": "6.18.58",
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                    "lessThanOrEqual": "7.2.*",
                    "status": "unaffected",
                    "version": "7.2.12",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "*",
                    "status": "unaffected",
                    "version": "7.3",
                    "versionType": "original_commit_for_fix"
                  }
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              }
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          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix heap out-of-bounds write in krb5_authenticate()\n\nIn krb5_authenticate(), out_len is calculated to determine available\nheadroom in response_buf for the incoming Kerberos AP-REP token. However,\nwhen SMB2_SESSION_SETUP is processed as a non-first element of a compounded\nSMB2 request, the calculation omits work-\u003enext_smb2_rsp_hdr_off.\n\nThis causes out_len to overstate remaining buffer headroom by\nthe cumulative size of prior responses in the compound chain. Consequently,\nthe length check in ksmbd_krb5_authenticate()\n(*out_len \u003c= resp-\u003espnego_blob_len) passes erroneously, allowing memcpy()\nto write the AP-REP blob past the end of response_buf into adjacent kernel\nheap memory.\n\nFix this by subtracting work-\u003enext_smb2_rsp_hdr_off when computing out_len,\nensuring it accurately reflects physical remaining buffer space."
          }
        ],
        "id": "CVE-2026-99083",
        "lastModified": "2026-10-26T07:17:18.627",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
                "availabilityImpact": "HIGH",
                "baseScore": 8.8,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
                "version": "3.1"
              },
              "exploitabilityScore": 2.8,
              "impactScore": 5.9,
              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
            }
          ]
        },
        "published": "2026-10-23T13:17:32.577",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/23a0be6a84a38ac169eeab49017934e8e27c65f0"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/4722d06b2907585074252061b1024a696c1cfc23"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/517404e157395d0f8da125ca956c566895dfcd06"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/59c6dcc5dd9dafe764ca0d40525933b2be69b059"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/80af1bde97d5a85ad6f2c40ca894ccc8fa75a27a"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Critical",
      "current_release_date": "2026-10-26T17:53:08+00:00",
      "cve": "CVE-2026-99083",
      "id": "CVE-2026-99083",
      "initial_release_date": "2026-10-23T00:00:00+00:00",
      "product_status:known_not_affected": "278",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ksmbd: fix heap out-of-bounds write in krb5_authenticate()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-99083.json",
      "version": "3"
    }
  }
}

FKIE_CVE-2026-99083

Vulnerability from fkie_nvd - Published: 2026-10-23 13:17 - Updated: 2026-10-26 07:17

Severity

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

Summary

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/23a0be6a84a38ac169eeab49017934e8e27c65f0
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/4722d06b2907585074252061b1024a696c1cfc23
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/517404e157395d0f8da125ca956c566895dfcd06
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/59c6dcc5dd9dafe764ca0d40525933b2be69b059
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/80af1bde97d5a85ad6f2c40ca894ccc8fa75a27a

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/smb2pdu.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "59c6dcc5dd9dafe764ca0d40525933b2be69b059",
              "status": "affected",
              "version": "98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8",
              "versionType": "git"
            },
            {
              "lessThan": "80af1bde97d5a85ad6f2c40ca894ccc8fa75a27a",
              "status": "affected",
              "version": "98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8",
              "versionType": "git"
            },
            {
              "lessThan": "517404e157395d0f8da125ca956c566895dfcd06",
              "status": "affected",
              "version": "98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8",
              "versionType": "git"
            },
            {
              "lessThan": "4722d06b2907585074252061b1024a696c1cfc23",
              "status": "affected",
              "version": "98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8",
              "versionType": "git"
            },
            {
              "lessThan": "23a0be6a84a38ac169eeab49017934e8e27c65f0",
              "status": "affected",
              "version": "98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "676392184785ace61e939831e7ca44a03d438c3b",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "ef572ffa8eb44111eed2925fbb2adca78bdcbf61",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "2ba03cecb12ac7ac9e0170e251543c56832d9959",
              "versionType": "git"
            },
            {
              "lessThan": "5.16",
              "status": "affected",
              "version": "5.15.145",
              "versionType": "semver"
            },
            {
              "lessThan": "6.2",
              "status": "affected",
              "version": "6.1.40",
              "versionType": "semver"
            },
            {
              "lessThan": "6.5",
              "status": "affected",
              "version": "6.4.5",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/smb2pdu.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.5"
            },
            {
              "lessThan": "6.5",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.160",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.114",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.58",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.12",
              "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\nksmbd: fix heap out-of-bounds write in krb5_authenticate()\n\nIn krb5_authenticate(), out_len is calculated to determine available\nheadroom in response_buf for the incoming Kerberos AP-REP token. However,\nwhen SMB2_SESSION_SETUP is processed as a non-first element of a compounded\nSMB2 request, the calculation omits work-\u003enext_smb2_rsp_hdr_off.\n\nThis causes out_len to overstate remaining buffer headroom by\nthe cumulative size of prior responses in the compound chain. Consequently,\nthe length check in ksmbd_krb5_authenticate()\n(*out_len \u003c= resp-\u003espnego_blob_len) passes erroneously, allowing memcpy()\nto write the AP-REP blob past the end of response_buf into adjacent kernel\nheap memory.\n\nFix this by subtracting work-\u003enext_smb2_rsp_hdr_off when computing out_len,\nensuring it accurately reflects physical remaining buffer space."
    }
  ],
  "id": "CVE-2026-99083",
  "lastModified": "2026-10-26T07:17:18.627",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 8.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-10-23T13:17:32.577",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/23a0be6a84a38ac169eeab49017934e8e27c65f0"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/4722d06b2907585074252061b1024a696c1cfc23"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/517404e157395d0f8da125ca956c566895dfcd06"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/59c6dcc5dd9dafe764ca0d40525933b2be69b059"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/80af1bde97d5a85ad6f2c40ca894ccc8fa75a27a"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}

GHSA-2J87-48P3-J5XW

Vulnerability from github – Published: 2026-10-23 15:31 – Updated: 2026-10-24 15:32

Details

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

ksmbd: fix heap out-of-bounds write in krb5_authenticate()

In krb5_authenticate(), out_len is calculated to determine available headroom in response_buf for the incoming Kerberos AP-REP token. However, when SMB2_SESSION_SETUP is processed as a non-first element of a compounded SMB2 request, the calculation omits work->next_smb2_rsp_hdr_off.

This causes out_len to overstate remaining buffer headroom by the cumulative size of prior responses in the compound chain. Consequently, the length check in ksmbd_krb5_authenticate() (*out_len <= resp->spnego_blob_len) passes erroneously, allowing memcpy() to write the AP-REP blob past the end of response_buf into adjacent kernel heap memory.

Fix this by subtracting work->next_smb2_rsp_hdr_off when computing out_len, ensuring it accurately reflects physical remaining buffer space.

Severity

8.8 (High)


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

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-99083"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-23T13:17:32Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix heap out-of-bounds write in krb5_authenticate()\n\nIn krb5_authenticate(), out_len is calculated to determine available\nheadroom in response_buf for the incoming Kerberos AP-REP token. However,\nwhen SMB2_SESSION_SETUP is processed as a non-first element of a compounded\nSMB2 request, the calculation omits work-\u003enext_smb2_rsp_hdr_off.\n\nThis causes out_len to overstate remaining buffer headroom by\nthe cumulative size of prior responses in the compound chain. Consequently,\nthe length check in ksmbd_krb5_authenticate()\n(*out_len \u003c= resp-\u003espnego_blob_len) passes erroneously, allowing memcpy()\nto write the AP-REP blob past the end of response_buf into adjacent kernel\nheap memory.\n\nFix this by subtracting work-\u003enext_smb2_rsp_hdr_off when computing out_len,\nensuring it accurately reflects physical remaining buffer space.",
  "id": "GHSA-2j87-48p3-j5xw",
  "modified": "2026-10-24T15:32:51Z",
  "published": "2026-10-23T15:31:37Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99083"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/23a0be6a84a38ac169eeab49017934e8e27c65f0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4722d06b2907585074252061b1024a696c1cfc23"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/517404e157395d0f8da125ca956c566895dfcd06"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/59c6dcc5dd9dafe764ca0d40525933b2be69b059"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/80af1bde97d5a85ad6f2c40ca894ccc8fa75a27a"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

MSRC_CVE-2026-99083

Vulnerability from csaf_microsoft - Published: 2026-10-25 01:05 - Updated: 2026-10-25 01:06

Summary

ksmbd: fix heap out-of-bounds write in krb5_authenticate()

Scope

1 vulnerability in this advisory, including CVE-2026-99083.

CVE-2026-99083

Under investigation: 2 products

Open the full advisory

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.

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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.
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CVE-2026-99083 (GCVE-0-2026-99083)

FKIE_CVE-2026-99083

GHSA-2J87-48P3-J5XW

MSRC_CVE-2026-99083

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