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drm/hyperv: validate VMBus packet size in receive callback

Type: advisorySource: OSV1 source record

In the Linux kernel, the following vulnerability has been resolved: drm/hyperv: validate VMBus packet size in receive callback hyperv_receive_sub() reads msg->vid_hdr.type and dispatches into one of four message-type branches without knowing how many bytes the host wrote into hv->recv_buf. The completion path then runs memcpy(hv->init_buf, msg, VMBUS_MAX_PACKET_SIZE), so the consumer that wakes on wait_for_completion_timeout() can read up to 16 KiB of residue from a prior message as if it were the response payload. Pass bytes_recvd into hyperv_receive_sub() and reject any packet that does not cover the pipe + synthvid header. A single switch on msg->vid_hdr.type then computes the type-specific payload size: the three completion-driving types (SYNTHVID_VERSION_RESPONSE, SYNTHVID_RESOLUTION_RESPONSE, SYNTHVID_VRAM_LOCATION_ACK) fall through to a shared exit that requires that size before memcpy/complete, while SYNTHVID_FEATURE_CHANGE validates its own payload and returns before reading is_dirt_needed. Unknown types are dropped. SYNTHVID_RESOLUTION_RESPONSE is variable length: the host fills resolution_count entries, not the full SYNTHVID_MAX_RESOLUTION_COUNT array. Validate the fixed prefix first so resolution_count can be read, bound it against the array, then require only the count-sized array, so the shorter responses the host actually sends are accepted. Only run the sub-handler when vmbus_recvpacket() returned success. The memcpy length is bytes_recvd, which is bounded by

Announced Source revision 1
Original source ↗

CVE-2026-64527

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: osv:CVE-2026-64527

Kernel

Source reference: /affected/1/package/name

Affected versions
Not stated in this record
Fixed versions
5.15.210

Source reference: /affected/1/ranges

6.1.176

Source reference: /affected/1/ranges

6.6.143

Source reference: /affected/1/ranges

6.12.93

Source reference: /affected/1/ranges

6.18.35

Source reference: /affected/1/ranges

7.0.12

Source reference: /affected/1/ranges

Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "ranges": [
      {
        "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
        "type": "GIT",
        "events": [
          {
            "introduced": "76c56a5affeba1e163b66b9d8cc192e6154466f0"
          },
          {
            "fixed": "57d5d697642e05d5dd2d40660817765943dd709f"
          },
          {
            "fixed": "f5251226551bfec98c4705641b6f94ff1f238d91"
          },
          {
            "fixed": "049a6b474823049fe60212f25f26e4b30f44ee8f"
          },
          {
            "fixed": "588c84b461393ff1998ac7b97b04f953f642e0df"
          },
          {
            "fixed": "164dc7bf17609340233c6bf4f66bb7c7008a0511"
          },
          {
            "fixed": "c8974d96b6a5496f33dc69a3ce28a7bf5078def4"
          },
          {
            "fixed": "7f87763f47a3c22fb50265a00619ef10f2394b18"
          }
        ]
      }
    ],
    "database_specific": {
      "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64527.json"
    }
  },
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "5.14.0"
          },
          {
            "fixed": "5.15.210"
          }
        ]
      },
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "5.16.0"
          },
          {
            "fixed": "6.1.176"
          }
        ]
      },
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "6.2.0"
          },
          {
            "fixed": "6.6.143"
          }
        ]
      },
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "6.7.0"
          },
          {
            "fixed": "6.12.93"
          }
        ]
      },
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "6.13.0"
          },
          {
            "fixed": "6.18.35"
          }
        ]
      },
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "6.19.0"
          },
          {
            "fixed": "7.0.12"
          }
        ]
      }
    ],
    "package": {
      "name": "Kernel",
      "ecosystem": "Linux"
    },
    "database_specific": {
      "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64527.json"
    }
  }
]
Related CVEs
CVE-2026-64527

Source reference: /id

Publisher severity

No explicit severity was provided.

Event
#50840 · Revision 1
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Publisher date
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