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CVE-2026-74277 (GCVE-0-2026-74277)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:57 – Updated: 2026-08-17 05:45
VLAI
Title
iommu/dma-iommu: Fix wrong scatterlist length assignment in P2PDMA path
Summary
In the Linux kernel, the following vulnerability has been resolved: iommu/dma-iommu: Fix wrong scatterlist length assignment in P2PDMA path In iommu_dma_map_sg(), when handling PCI P2PDMA cases, the DMA length of the current scatterlist segment `s` is incorrectly assigned from the head entry `sg->length` instead of the current entry `s->length`. This typo causes all P2PDMA segments in the scatterlist to inherit the length of the first segment, leading to corrupted DMA lengths for multi- segment scatterlists. Fix this by using `s->length` instead of `sg->length`.
Severity
8.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: a25e7962db0d79882c9d32fd2a67a02e79129c0e , < 8646f00ce021e49f4f05bc1d4060a0c27b25d0e1 (git)
Affected: a25e7962db0d79882c9d32fd2a67a02e79129c0e , < db50fb87015b955a5a0c155293b2dd40d63a3b9e (git)
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Linux Linux Affected: 6.16
Unaffected: 0 , < 6.16 (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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        }
      ],
      "metrics": [
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
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              "lang": "en",
              "value": "AV:L - Exploitation requires local block/RDMA I/O that reaches dma_map_sg()/ib_dma_map_sg()\u2192iommu_dma_map_sg() with multi-segment PCI P2PDMA scatterlists (e.g., NVMe-RDMA host, apple_nvme) on IOMMU-enabled systems; no direct remote packet handler invokes this mapping path.\nAC:L - An attacker can reliably trigger the bug by crafting I/O sizes and alignments that yield multi-segment scatterlists with differing P2PDMA segment lengths; no uncontrollable heap layout, timing race, or rare victim state is required beyond P2PDMA-capable hardware topology.\nPR:L - Any unprivileged local user with permission to perform I/O on a PCI device engaged in P2PDMA transfers (typical GPU/compute or storage device access) can trigger the corrupted mapping; real root in the init namespace is not required and user namespaces do not grant this capability.\nUI:N - No victim user action is needed beyond the attacker issuing their own read/write or RDMA/block I/O; exploitation does not depend on a separate user opening files, mounting filesystems, or clicking anything.\nS:C - Incorrect sg_dma_len values let PCIe DMA engines perform bus-address transfers beyond the intended buffer, bypassing IOMMU/DMA isolation and allowing a device\u2019s DMA scope to affect host memory outside the mapped region.\nC:H - When the first segment length exceeds a later P2PDMA segment\u2019s true length, inflated DMA metadata causes the device to read past the buffer end over PCI, enabling disclosure of adjacent device or host memory comparable to an out-of-bounds DMA read.\nI:H - Corrupted DMA lengths permit out-of-bounds PCIe DMA writes beyond the allocated P2PDMA buffer, corrupting adjacent memory and providing a memory-corruption primitive that can be leveraged for further compromise of kernel-adjacent data.\nA:H - Out-of-bounds DMA transfers can trigger IOMMU faults, device errors, and kernel oops/panics when hardware accesses unmapped or protected regions, and the corrupted mappings persist until unmap, enabling repeatable disruption."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:45:18.964Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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      "references": [
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          "url": "https://git.kernel.org/stable/c/8646f00ce021e49f4f05bc1d4060a0c27b25d0e1"
        },
        {
          "url": "https://git.kernel.org/stable/c/db50fb87015b955a5a0c155293b2dd40d63a3b9e"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74277",
    "datePublished": "2026-08-15T05:57:48.814Z",
    "dateReserved": "2026-08-15T05:44:03.880Z",
    "dateUpdated": "2026-08-17T05:45:18.964Z",
    "state": "PUBLISHED"
  },
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      "date": "2026-09-04",
      "epss": "0.00154",
      "percentile": "0.04841"
    },
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-20T15:04:31+00:00",
      "cve": "CVE-2026-74277",
      "id": "CVE-2026-74277",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "90",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: iommu/dma-iommu: Fix wrong scatterlist length assignment in P2PDMA path",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-74277.json",
      "version": "3"
    }
  }
}



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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.
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  • 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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