CVE-2026-31476 (GCVE-0-2026-31476)

Vulnerability from cvelistv5 – Published: 2026-04-22 13:54 – Updated: 2026-04-22 13:54
VLAI?
Title
ksmbd: do not expire session on binding failure
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: do not expire session on binding failure When a multichannel session binding request fails (e.g. wrong password), the error path unconditionally sets sess->state = SMB2_SESSION_EXPIRED. However, during binding, sess points to the target session looked up via ksmbd_session_lookup_slowpath() -- which belongs to another connection's user. This allows a remote attacker to invalidate any active session by simply sending a binding request with a wrong password (DoS). Fix this by skipping session expiration when the failed request was a binding attempt, since the session does not belong to the current connection. The reference taken by ksmbd_session_lookup_slowpath() is still correctly released via ksmbd_user_session_put().
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < f5300690c23c5ac860499bb37dbc09cf43fd62e6 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 6fafc4c4238e538969f1375f9ecdc6587c53f1cc (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 1d1888b4a7aec518b707f6eca0bf08992c0e8da3 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < a897064a457056acb976e20e3007cdf553de340f (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < e0e5edc81b241c70355217de7e120c97c3429deb (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 9bbb19d21ded7d78645506f20d8c44895e3d0fb9 (git)
Create a notification for this product.
    Linux Linux Unaffected: 6.1.168 , ≤ 6.1.* (semver)
Unaffected: 6.6.131 , ≤ 6.6.* (semver)
Unaffected: 6.12.80 , ≤ 6.12.* (semver)
Unaffected: 6.18.21 , ≤ 6.18.* (semver)
Unaffected: 6.19.11 , ≤ 6.19.* (semver)
Unaffected: 7.0 , ≤ * (original_commit_for_fix)
Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "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": "f5300690c23c5ac860499bb37dbc09cf43fd62e6",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "6fafc4c4238e538969f1375f9ecdc6587c53f1cc",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "1d1888b4a7aec518b707f6eca0bf08992c0e8da3",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "a897064a457056acb976e20e3007cdf553de340f",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "e0e5edc81b241c70355217de7e120c97c3429deb",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "9bbb19d21ded7d78645506f20d8c44895e3d0fb9",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            }
          ]
        },
        {
          "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": [
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.168",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.131",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.80",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.21",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.168",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.131",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.80",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.21",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.11",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: do not expire session on binding failure\n\nWhen a multichannel session binding request fails (e.g. wrong password),\nthe error path unconditionally sets sess-\u003estate = SMB2_SESSION_EXPIRED.\nHowever, during binding, sess points to the target session looked up via\nksmbd_session_lookup_slowpath() -- which belongs to another connection\u0027s\nuser. This allows a remote attacker to invalidate any active session by\nsimply sending a binding request with a wrong password (DoS).\n\nFix this by skipping session expiration when the failed request was\na binding attempt, since the session does not belong to the current\nconnection. The reference taken by ksmbd_session_lookup_slowpath() is\nstill correctly released via ksmbd_user_session_put()."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-22T13:54:04.779Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/f5300690c23c5ac860499bb37dbc09cf43fd62e6"
        },
        {
          "url": "https://git.kernel.org/stable/c/6fafc4c4238e538969f1375f9ecdc6587c53f1cc"
        },
        {
          "url": "https://git.kernel.org/stable/c/1d1888b4a7aec518b707f6eca0bf08992c0e8da3"
        },
        {
          "url": "https://git.kernel.org/stable/c/a897064a457056acb976e20e3007cdf553de340f"
        },
        {
          "url": "https://git.kernel.org/stable/c/e0e5edc81b241c70355217de7e120c97c3429deb"
        },
        {
          "url": "https://git.kernel.org/stable/c/9bbb19d21ded7d78645506f20d8c44895e3d0fb9"
        }
      ],
      "title": "ksmbd: do not expire session on binding failure",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-31476",
    "datePublished": "2026-04-22T13:54:04.779Z",
    "dateReserved": "2026-03-09T15:48:24.098Z",
    "dateUpdated": "2026-04-22T13:54:04.779Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-31476",
      "date": "2026-04-23",
      "epss": "0.00076",
      "percentile": "0.22786"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-31476\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-04-22T14:16:44.337\",\"lastModified\":\"2026-04-23T16:17:41.280\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nksmbd: do not expire session on binding failure\\n\\nWhen a multichannel session binding request fails (e.g. wrong password),\\nthe error path unconditionally sets sess-\u003estate = SMB2_SESSION_EXPIRED.\\nHowever, during binding, sess points to the target session looked up via\\nksmbd_session_lookup_slowpath() -- which belongs to another connection\u0027s\\nuser. This allows a remote attacker to invalidate any active session by\\nsimply sending a binding request with a wrong password (DoS).\\n\\nFix this by skipping session expiration when the failed request was\\na binding attempt, since the session does not belong to the current\\nconnection. The reference taken by ksmbd_session_lookup_slowpath() is\\nstill correctly released via ksmbd_user_session_put().\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/1d1888b4a7aec518b707f6eca0bf08992c0e8da3\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/6fafc4c4238e538969f1375f9ecdc6587c53f1cc\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/9bbb19d21ded7d78645506f20d8c44895e3d0fb9\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/a897064a457056acb976e20e3007cdf553de340f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/e0e5edc81b241c70355217de7e120c97c3429deb\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/f5300690c23c5ac860499bb37dbc09cf43fd62e6\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

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.