Vulnerability-Lookup

FKIE_CVE-2026-89690

Vulnerability from fkie_nvd - Published: 2026-09-11 20:19 - Updated: 2026-09-13 07:17

Severity

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

Summary

In the Linux kernel, the following vulnerability has been resolved: nfsd: defer vfree of compound ops to fix rpc_status UAF The rpc_status netlink dumpit walks every in-flight svc_rqst under rcu_read_lock and, for NFSv4 requests, reads opnums out of args->ops[]. But args->ops is a separate vmalloc buffer freed synchronously by vfree() in nfsd4_release_compoundargs() at the end of every compound. The dumpit's rcu_read_lock pins the svc_rqst struct itself (freed via kfree_rcu), but nothing defers the vfree of the ops buffer across the RCU grace period. A concurrent compound completion can therefore free the buffer while the dumpit is reading it — a use-after-free on vmalloc memory. The trailing seqcount recheck (smp_load_acquire of rq_status_counter) cannot undo a load that already retired against freed memory. Fix by replacing vfree(args->ops) with kvfree_rcu_mightsleep(), which defers the free until after an RCU grace period. This makes the existing rcu_read_lock in the dumpit sufficient to protect the read. The tradeoff is that completed compound ops buffers (up to 200 * sizeof(struct nfsd4_op)) persist in memory slightly longer, across one grace period, before being reclaimed.

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/19413ccc45070a7270b9e25c2a258daf7f91de42
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/48f72aff24f7a7329209dc6cbc27c869f3e3595c
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/6703199f4d7e7f37d6a726a849eb358e8fae72fb
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/fca26a3fc19ed02278aa2a150af82d43db0302cb

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/nfs4xdr.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "48f72aff24f7a7329209dc6cbc27c869f3e3595c",
              "status": "affected",
              "version": "bd9d6a3efa9709e653aafbeb859289feccb8e70c",
              "versionType": "git"
            },
            {
              "lessThan": "6703199f4d7e7f37d6a726a849eb358e8fae72fb",
              "status": "affected",
              "version": "bd9d6a3efa9709e653aafbeb859289feccb8e70c",
              "versionType": "git"
            },
            {
              "lessThan": "19413ccc45070a7270b9e25c2a258daf7f91de42",
              "status": "affected",
              "version": "bd9d6a3efa9709e653aafbeb859289feccb8e70c",
              "versionType": "git"
            },
            {
              "lessThan": "fca26a3fc19ed02278aa2a150af82d43db0302cb",
              "status": "affected",
              "version": "bd9d6a3efa9709e653aafbeb859289feccb8e70c",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/nfs4xdr.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.7"
            },
            {
              "lessThan": "6.7",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.109",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.50",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "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: defer vfree of compound ops to fix rpc_status UAF\n\nThe rpc_status netlink dumpit walks every in-flight svc_rqst under\nrcu_read_lock and, for NFSv4 requests, reads opnums out of\nargs-\u003eops[]. But args-\u003eops is a separate vmalloc buffer freed\nsynchronously by vfree() in nfsd4_release_compoundargs() at the end\nof every compound. The dumpit\u0027s rcu_read_lock pins the svc_rqst\nstruct itself (freed via kfree_rcu), but nothing defers the vfree\nof the ops buffer across the RCU grace period. A concurrent compound\ncompletion can therefore free the buffer while the dumpit is reading\nit \u2014 a use-after-free on vmalloc memory.\n\nThe trailing seqcount recheck (smp_load_acquire of rq_status_counter)\ncannot undo a load that already retired against freed memory.\n\nFix by replacing vfree(args-\u003eops) with kvfree_rcu_mightsleep(), which\ndefers the free until after an RCU grace period. This makes the\nexisting rcu_read_lock in the dumpit sufficient to protect the read.\nThe tradeoff is that completed compound ops buffers (up to\n200 * sizeof(struct nfsd4_op)) persist in memory slightly longer,\nacross one grace period, before being reclaimed."
    }
  ],
  "id": "CVE-2026-89690",
  "lastModified": "2026-09-13T07:17:34.850",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-09-11T20:19:56.030",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/19413ccc45070a7270b9e25c2a258daf7f91de42"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/48f72aff24f7a7329209dc6cbc27c869f3e3595c"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6703199f4d7e7f37d6a726a849eb358e8fae72fb"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/fca26a3fc19ed02278aa2a150af82d43db0302cb"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}

CVE-2026-89690 (GCVE-0-2026-89690)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:46 – Updated: 2026-09-13 06:33

Title

nfsd: defer vfree of compound ops to fix rpc_status UAF

Summary

Severity

7.8 (High)


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

Assigner

Linux mitre root

References

4 references

URL	Tags
https://git.kernel.org/stable/c/48f72aff24f7a7329…
https://git.kernel.org/stable/c/6703199f4d7e7f37d…
https://git.kernel.org/stable/c/19413ccc45070a727…
https://git.kernel.org/stable/c/fca26a3fc19ed0227…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: bd9d6a3efa9709e653aafbeb859289feccb8e70c , < 48f72aff24f7a7329209dc6cbc27c869f3e3595c (git) Affected: bd9d6a3efa9709e653aafbeb859289feccb8e70c , < 6703199f4d7e7f37d6a726a849eb358e8fae72fb (git) Affected: bd9d6a3efa9709e653aafbeb859289feccb8e70c , < 19413ccc45070a7270b9e25c2a258daf7f91de42 (git) Affected: bd9d6a3efa9709e653aafbeb859289feccb8e70c , < fca26a3fc19ed02278aa2a150af82d43db0302cb (git)
Linux	Linux	Affected: 6.7 Unaffected: 0 , < 6.7 (semver) Unaffected: 6.12.109 , ≤ 6.12.* (semver) Unaffected: 6.18.50 , ≤ 6.18.* (semver) Unaffected: 7.2.4 , ≤ 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/nfs4xdr.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "48f72aff24f7a7329209dc6cbc27c869f3e3595c",
              "status": "affected",
              "version": "bd9d6a3efa9709e653aafbeb859289feccb8e70c",
              "versionType": "git"
            },
            {
              "lessThan": "6703199f4d7e7f37d6a726a849eb358e8fae72fb",
              "status": "affected",
              "version": "bd9d6a3efa9709e653aafbeb859289feccb8e70c",
              "versionType": "git"
            },
            {
              "lessThan": "19413ccc45070a7270b9e25c2a258daf7f91de42",
              "status": "affected",
              "version": "bd9d6a3efa9709e653aafbeb859289feccb8e70c",
              "versionType": "git"
            },
            {
              "lessThan": "fca26a3fc19ed02278aa2a150af82d43db0302cb",
              "status": "affected",
              "version": "bd9d6a3efa9709e653aafbeb859289feccb8e70c",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/nfs4xdr.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.7"
            },
            {
              "lessThan": "6.7",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.109",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.50",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "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": "6.12.109",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.50",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.4",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc1",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: defer vfree of compound ops to fix rpc_status UAF\n\nThe rpc_status netlink dumpit walks every in-flight svc_rqst under\nrcu_read_lock and, for NFSv4 requests, reads opnums out of\nargs-\u003eops[]. But args-\u003eops is a separate vmalloc buffer freed\nsynchronously by vfree() in nfsd4_release_compoundargs() at the end\nof every compound. The dumpit\u0027s rcu_read_lock pins the svc_rqst\nstruct itself (freed via kfree_rcu), but nothing defers the vfree\nof the ops buffer across the RCU grace period. A concurrent compound\ncompletion can therefore free the buffer while the dumpit is reading\nit \u2014 a use-after-free on vmalloc memory.\n\nThe trailing seqcount recheck (smp_load_acquire of rq_status_counter)\ncannot undo a load that already retired against freed memory.\n\nFix by replacing vfree(args-\u003eops) with kvfree_rcu_mightsleep(), which\ndefers the free until after an RCU grace period. This makes the\nexisting rcu_read_lock in the dumpit sufficient to protect the read.\nThe tradeoff is that completed compound ops buffers (up to\n200 * sizeof(struct nfsd4_op)) persist in memory slightly longer,\nacross one grace period, before being reclaimed."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The UAF is in nfsd_nl_rpc_status_get_dumpit(), reached only via the NFSD_CMD_RPC_STATUS_GET generic-netlink dump over AF_NETLINK. Remote NFSv4 compounds drive the vfree of args-\u003eops in nfsd4_release_compoundargs() but never enter dumpit, so exploitation requires local access.\nAC:L - The attacker fully controls the dumpit reader and can loop it while sending NFSv4 COMPOUNDs with more than eight ops so nfsd vcalloc()s args-\u003eops and vfree()s it on every request. That is an attacker-driven race; the seqcount recheck does not prevent the already-retired load against freed vmalloc memory.\nPR:L - NFSD_CMD_RPC_STATUS_GET is registered with GENL_CMD_CAP_DUMP and no GENL_ADMIN_PERM, so any unprivileged process in the nfsd network namespace can invoke the dump. Exploitation does not require CAP_NET_ADMIN or root.\nUI:N - The attacker issues the netlink dump themselves and can generate the concurrent NFSv4 compounds; no separate victim action such as mounting a filesystem or opening a device is required.\nS:U - This is a kernel vmalloc use-after-free in nfsd on the local host. Impact stays inside the kernel\u0027s security authority and does not cross a VM, IOMMU, or other security boundary.\nC:H - dumpit reads opnums from the vfree\u0027d args-\u003eops[] buffer and returns them to userspace via NFSD_A_RPC_STATUS_COMPOUND_OPS. A kernel UAF with reuse of that vmalloc region yields an arbitrary-read primitive, which CVSS treats as high confidentiality impact.\nI:H - This is a use-after-free of a vmalloc compound-ops array that dumpit walks under rcu_read_lock while nfsd vfree()s it. UAF of attacker-reclaimable kernel memory enables corruption and control-flow hijacking primitives, not crash-only impact.\nA:H - Use-after-free of a vfree\u0027d vmalloc buffer while dumpit still loads args-\u003eops[j].opnum oopses or panics the kernel even if the UAF is not turned into code execution, fully disrupting the NFS server host."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-13T06:33:14.771Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/48f72aff24f7a7329209dc6cbc27c869f3e3595c"
        },
        {
          "url": "https://git.kernel.org/stable/c/6703199f4d7e7f37d6a726a849eb358e8fae72fb"
        },
        {
          "url": "https://git.kernel.org/stable/c/19413ccc45070a7270b9e25c2a258daf7f91de42"
        },
        {
          "url": "https://git.kernel.org/stable/c/fca26a3fc19ed02278aa2a150af82d43db0302cb"
        }
      ],
      "title": "nfsd: defer vfree of compound ops to fix rpc_status UAF",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89690",
    "datePublished": "2026-09-11T19:46:10.632Z",
    "dateReserved": "2026-09-11T19:38:34.749Z",
    "dateUpdated": "2026-09-13T06:33:14.771Z",
    "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.

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.