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GHSA-RFXQ-R256-5MJ8

Vulnerability from github – Published: 2026-09-24 18:31 – Updated: 2026-09-25 06:30

Details

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

RDMA/umem: Be careful about boundary conditions in ib_umem_find_best_pgsz()

Several corner cases, especially important on 32 bits:

umem->iova is u64, the function argument should pass in u64 or iova will be truncated
Check that the length is not too large for the iova
Check that lengths > 4G don't overflow the GENMASK

Severity

7.8 (High)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-97421"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-24T17:17:19Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/umem: Be careful about boundary conditions in ib_umem_find_best_pgsz()\n\nSeveral corner cases, especially important on 32 bits:\n\n- umem-\u003eiova is u64, the function argument should pass in u64 or\n  iova will be truncated\n- Check that the length is not too large for the iova\n- Check that lengths \u003e 4G don\u0027t overflow the GENMASK",
  "id": "GHSA-rfxq-r256-5mj8",
  "modified": "2026-09-25T06:30:31Z",
  "published": "2026-09-24T18:31:32Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-97421"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/09ea6837a0434fb4db99528a5055b6d822135dcf"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5fc5b73109540809b094710fac44da81dd8a3ff8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ae3cf7d2c4d506c5c91746321644e1a08d989e2a"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-97421 (GCVE-0-2026-97421)

Vulnerability from cvelistv5 – Published: 2026-09-24 16:03 – Updated: 2026-09-25 12:43

Title

RDMA/umem: Be careful about boundary conditions in ib_umem_find_best_pgsz()

Summary

In the Linux kernel, the following vulnerability has been resolved: RDMA/umem: Be careful about boundary conditions in ib_umem_find_best_pgsz() Several corner cases, especially important on 32 bits: - umem->iova is u64, the function argument should pass in u64 or iova will be truncated - Check that the length is not too large for the iova - Check that lengths > 4G don't overflow the GENMASK

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

3 references

URL	Tags
https://git.kernel.org/stable/c/ae3cf7d2c4d506c5c…
https://git.kernel.org/stable/c/5fc5b73109540809b…
https://git.kernel.org/stable/c/09ea6837a0434fb4d…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: a40c20dabdf9045270767c75918feb67f0727c89 , < ae3cf7d2c4d506c5c91746321644e1a08d989e2a (git) Affected: a40c20dabdf9045270767c75918feb67f0727c89 , < 5fc5b73109540809b094710fac44da81dd8a3ff8 (git) Affected: a40c20dabdf9045270767c75918feb67f0727c89 , < 09ea6837a0434fb4db99528a5055b6d822135dcf (git) Affected: 85e40ba1c4a5246b35e91c2ed69d4680426904d7 (git) Affected: 59f07434b297e2268f5d5c567db5b09145245cf1 (git) Affected: 488229b7729d7becf4c39c5e74fb709fb35115c2 (git) Affected: 5.4.73 , < 5.5 (semver) Affected: 5.8.17 , < 5.9 (semver) Affected: 5.9.2 , < 5.10 (semver)
Linux	Linux	Affected: 5.10 Unaffected: 0 , < 5.10 (semver) Unaffected: 6.12.111 , ≤ 6.12.* (semver) Unaffected: 6.18.53 , ≤ 6.18.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/infiniband/core/umem.c",
            "include/rdma/ib_umem.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "ae3cf7d2c4d506c5c91746321644e1a08d989e2a",
              "status": "affected",
              "version": "a40c20dabdf9045270767c75918feb67f0727c89",
              "versionType": "git"
            },
            {
              "lessThan": "5fc5b73109540809b094710fac44da81dd8a3ff8",
              "status": "affected",
              "version": "a40c20dabdf9045270767c75918feb67f0727c89",
              "versionType": "git"
            },
            {
              "lessThan": "09ea6837a0434fb4db99528a5055b6d822135dcf",
              "status": "affected",
              "version": "a40c20dabdf9045270767c75918feb67f0727c89",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "85e40ba1c4a5246b35e91c2ed69d4680426904d7",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "59f07434b297e2268f5d5c567db5b09145245cf1",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "488229b7729d7becf4c39c5e74fb709fb35115c2",
              "versionType": "git"
            },
            {
              "lessThan": "5.5",
              "status": "affected",
              "version": "5.4.73",
              "versionType": "semver"
            },
            {
              "lessThan": "5.9",
              "status": "affected",
              "version": "5.8.17",
              "versionType": "semver"
            },
            {
              "lessThan": "5.10",
              "status": "affected",
              "version": "5.9.2",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/infiniband/core/umem.c",
            "include/rdma/ib_umem.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.10"
            },
            {
              "lessThan": "5.10",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.111",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.53",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.111",
                  "versionStartIncluding": "5.10",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.53",
                  "versionStartIncluding": "5.10",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "5.10",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "5.4.73",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "5.8.17",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "5.9.2",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/umem: Be careful about boundary conditions in ib_umem_find_best_pgsz()\n\nSeveral corner cases, especially important on 32 bits:\n\n- umem-\u003eiova is u64, the function argument should pass in u64 or\n  iova will be truncated\n- Check that the length is not too large for the iova\n- Check that lengths \u003e 4G don\u0027t overflow the GENMASK"
        }
      ],
      "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 - Attacker-controlled cmd.hca_va and cmd.length reach ib_umem_find_best_pgsz() via open of /dev/infiniband/uverbsX, then ib_uverbs_write(IB_USER_VERBS_CMD_REG_MR)/ib_uverbs_reg_mr() or UVERBS_METHOD_REG_MR ioctl, then pd-\u003eops.reg_user_mr() (mlx5_ib_reg_user_mr/irdma_reg_user_mr/efa_register_mr). Remote RDMA packets do not supply virt or umem-\u003elength.\nAC:L - ib_uverbs_reg_mr() only requires (start \u0026 ~PAGE_MASK)==(hca_va \u0026 ~PAGE_MASK), so the attacker picks hca_va near 2^63 or U64_MAX with a small pinned region and makes (umem-\u003elength-1+virt) overflow or bits_per() return BITS_PER_LONG, hitting the unguarded GENMASK() deterministically with no race.\nPR:L - uverbs_devnode() creates /dev/infiniband/uverbs* mode 0666 and ib_uverbs_open() has no capability check (only rdma_dev_access_netns). ib_umem_get_va() needs can_do_mlock() (RLIMIT_MEMLOCK!=0) and ib_check_mr_access(); CAP_SYS_ADMIN/CAP_IPC_LOCK are not required.\nUI:N - After opening uverbs the attacker allocates a PD and issues IB_USER_VERBS_CMD_REG_MR or UVERBS_METHOD_REG_MR with their own start, length, and hca_va; no victim mount or other user action is required.\nS:U - A wrong page size or truncated umem-\u003eiova from ib_umem_find_best_pgsz() misprograms that host\u0027s RDMA MTT/PBL. This stays in the kernel/device memory-management authority and is not a KVM/Xen guest-to-host escape or IOMMU VM-boundary bypass.\nC:H - When bits_per((umem-\u003elength-1+virt)^virt)\u003e=BITS_PER_LONG, GENMASK(BITS_PER_LONG-1, bits) is invalid and mask can be 0, so the function returns rounddown_pow_of_two(pgsz_bitmap) (largest HW page). mlx5_ib_populate_pas()/rdma_umem_for_each_dma_block() then install oversized MTT/PBL entries, so the NIC DMA-reads physical memory beyond the pinned umem.\nI:H - The same oversized page size is programmed into hardware (efa_register_mr params.page_shift, ionic_pgtbl_init, mlx5 mkey PAS). With IB_ACCESS_LOCAL_WRITE or IB_ACCESS_REMOTE_WRITE from the REG_MR access_flags, the device DMA-writes outside the registered region, which is an arbitrary physical write.\nA:H - GENMASK() with l\u003eh is a shift UB that can oops (UBSAN) or yield mask==0; mis-sized pages cause IOMMU/device faults. ib_umem_is_contiguous() (mlx5_ib_db_map_user_desc, efa create_cq) can also treat a non-contiguous umem as one DMA block and fault the kernel or NIC."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-25T12:43:56.797Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/ae3cf7d2c4d506c5c91746321644e1a08d989e2a"
        },
        {
          "url": "https://git.kernel.org/stable/c/5fc5b73109540809b094710fac44da81dd8a3ff8"
        },
        {
          "url": "https://git.kernel.org/stable/c/09ea6837a0434fb4db99528a5055b6d822135dcf"
        }
      ],
      "title": "RDMA/umem: Be careful about boundary conditions in ib_umem_find_best_pgsz()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-97421",
    "datePublished": "2026-09-24T16:03:31.505Z",
    "dateReserved": "2026-09-24T14:53:16.868Z",
    "dateUpdated": "2026-09-25T12:43:56.797Z",
    "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.
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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.

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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GHSA-RFXQ-R256-5MJ8

CVE-2026-97421 (GCVE-0-2026-97421)

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