Vulnerability-Lookup

FKIE_CVE-2026-90038

Vulnerability from fkie_nvd - Published: 2026-09-16 11:17 - Updated: 2026-09-16 15:18

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: NFSD: Prevent client use-after-free during export state revocation nfsd4_revoke_export_states() has the same use-after-free as nfsd4_revoke_states(): it drops nn->client_lock across revoke_one_stid() and the following read of clp->cl_minorversion, but the stateid reference it holds does not pin the client. A teardown racing the dropped lock can free the client while revoke_one_stid() still dereferences it. exportfs -u drives this path through NFSD_CMD_UNLOCK_EXPORT, so an administrator removing an export can race a client expiry. Skip a client that is already expiring and otherwise pin it with cl_rpc_users under client_lock before dropping the lock, matching nfsd4_revoke_states().

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/2108de53568a64936a0da3e04d85c35df98d3fb6
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/c05ae58fe06ce2ac34312f649e71c3596bdde358

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/nfs4state.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "c05ae58fe06ce2ac34312f649e71c3596bdde358",
              "status": "affected",
              "version": "2eac189bb059d31a29937b29ee0f477394198610",
              "versionType": "git"
            },
            {
              "lessThan": "2108de53568a64936a0da3e04d85c35df98d3fb6",
              "status": "affected",
              "version": "2eac189bb059d31a29937b29ee0f477394198610",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/nfs4state.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.2"
            },
            {
              "lessThan": "7.2",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "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\nNFSD: Prevent client use-after-free during export state revocation\n\nnfsd4_revoke_export_states() has the same use-after-free as\nnfsd4_revoke_states(): it drops nn-\u003eclient_lock across\nrevoke_one_stid() and the following read of clp-\u003ecl_minorversion, but\nthe stateid reference it holds does not pin the client.  A teardown\nracing the dropped lock can free the client while revoke_one_stid()\nstill dereferences it.\n\nexportfs -u drives this path through NFSD_CMD_UNLOCK_EXPORT, so an\nadministrator removing an export can race a client expiry.\n\nSkip a client that is already expiring and otherwise pin it with\ncl_rpc_users under client_lock before dropping the lock, matching\nnfsd4_revoke_states()."
    }
  ],
  "id": "CVE-2026-90038",
  "lastModified": "2026-09-16T15:18:26.650",
  "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": "2026-09-16T11:17:17.010",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/2108de53568a64936a0da3e04d85c35df98d3fb6"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/c05ae58fe06ce2ac34312f649e71c3596bdde358"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}

CVE-2026-90038 (GCVE-0-2026-90038)

Vulnerability from cvelistv5 – Published: 2026-09-16 10:33 – Updated: 2026-09-16 14:41

Title

NFSD: Prevent client use-after-free during export state revocation

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

2 references

URL	Tags
https://git.kernel.org/stable/c/c05ae58fe06ce2ac3…
https://git.kernel.org/stable/c/2108de53568a64936…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 2eac189bb059d31a29937b29ee0f477394198610 , < c05ae58fe06ce2ac34312f649e71c3596bdde358 (git) Affected: 2eac189bb059d31a29937b29ee0f477394198610 , < 2108de53568a64936a0da3e04d85c35df98d3fb6 (git)
Linux	Linux	Affected: 7.2 Unaffected: 0 , < 7.2 (semver) Unaffected: 7.2.5 , ≤ 7.2.* (semver) Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/nfs4state.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "c05ae58fe06ce2ac34312f649e71c3596bdde358",
              "status": "affected",
              "version": "2eac189bb059d31a29937b29ee0f477394198610",
              "versionType": "git"
            },
            {
              "lessThan": "2108de53568a64936a0da3e04d85c35df98d3fb6",
              "status": "affected",
              "version": "2eac189bb059d31a29937b29ee0f477394198610",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/nfs4state.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.2"
            },
            {
              "lessThan": "7.2",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.5",
                  "versionStartIncluding": "7.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc1",
                  "versionStartIncluding": "7.2",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: Prevent client use-after-free during export state revocation\n\nnfsd4_revoke_export_states() has the same use-after-free as\nnfsd4_revoke_states(): it drops nn-\u003eclient_lock across\nrevoke_one_stid() and the following read of clp-\u003ecl_minorversion, but\nthe stateid reference it holds does not pin the client.  A teardown\nracing the dropped lock can free the client while revoke_one_stid()\nstill dereferences it.\n\nexportfs -u drives this path through NFSD_CMD_UNLOCK_EXPORT, so an\nadministrator removing an export can race a client expiry.\n\nSkip a client that is already expiring and otherwise pin it with\ncl_rpc_users under client_lock before dropping the lock, matching\nnfsd4_revoke_states()."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The UAF is in nfsd nfsd4_revoke_export_states(). A remote NFSv4 peer reaches the racing expire_client() over TCP/2049 via svc_recv to nfsd_dispatch to nfsd4_proc_compound: EXCHANGE_ID/CREATE_SESSION, SETCLIENTID_CONFIRM, or DESTROY_CLIENTID (ALLOWED_WITHOUT_FH), which free nfs4_client while the export-revoke walk still dereferences it.\nAC:L - The attacker controls the teardown side: they hold many stateids on the export so the revoke walk drops client_lock once per stid, and concurrently retry EXCHANGE_ID/CREATE_SESSION or SETCLIENTID_CONFIRM so mark_client_expired_locked() succeeds while cl_rpc_users is unpinned. The window is retryable and attacker-created.\nPR:N - EXCHANGE_ID, CREATE_SESSION, SETCLIENTID, SETCLIENTID_CONFIRM, and DESTROY_CLIENTID are ALLOWED_WITHOUT_FH with no export check. Typical AUTH_SYS/AUTH_NULL nfsd deployments do not verify RPC credentials, so any host that can reach TCP/2049 can establish state on an export and trigger expire.\nUI:N - The attacker drives the NFS compounds that create state and expire the client. Administrative exportfs -u / NFSD_CMD_UNLOCK_EXPORT is a server operational condition (unexport of the last client for a path so the filesystem can be unmounted), not a required victim user action.\nS:U - The freed object is struct nfs4_client in the NFS server kernel. Impact remains in that kernel security authority; there is no VM, IOMMU, or sandbox boundary crossing.\nC:H - revoke_one_stid() and the subsequent clp-\u003ecl_minorversion read dereference nfs4_client after free_client() kmem_cache_free\u0027s the mergeable client_slab object (KMEM_CACHE flags 0). Reclaim via EXCHANGE_ID discloses kernel memory; a UAF is C:H.\nI:H - revoke_one_stid() takes cl_lock and nfs4_put_stid() does refcount_dec_and_lock/idr_remove on the freed client\u0027s cl_lock/cl_stateids, concurrent with __destroy_client(), a slab UAF write primitive for heap corruption and control-flow hijacking.\nA:H - Use-after-free of nfs4_client in the nfsd export-revoke path oopses or panics the NFS server even without full exploitation, fully denying service of the host."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-16T14:41:51.107Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/c05ae58fe06ce2ac34312f649e71c3596bdde358"
        },
        {
          "url": "https://git.kernel.org/stable/c/2108de53568a64936a0da3e04d85c35df98d3fb6"
        }
      ],
      "title": "NFSD: Prevent client use-after-free during export state revocation",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90038",
    "datePublished": "2026-09-16T10:33:37.366Z",
    "dateReserved": "2026-09-11T19:38:34.782Z",
    "dateUpdated": "2026-09-16T14:41:51.107Z",
    "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.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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