GHSA-P23R-M2G4-23PQ

Vulnerability from github – Published: 2026-08-10 15:33 – Updated: 2026-08-19 18:32
VLAI
Details

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

drm/dp/mst: fix OOB reads in remote DPCD/I2C sideband reply parsers

drm_dp_sideband_parse_remote_dpcd_read() reads num_bytes from the raw message and then unconditionally does:

memcpy(bytes, &raw->msg[idx], num_bytes);

without checking that idx + num_bytes <= raw->curlen. raw->msg[] is 256 bytes; if a malicious or misbehaving MST hub sets num_bytes larger than the remaining payload, the memcpy reads past the received data into whatever follows in raw->msg[].

drm_dp_sideband_parse_remote_i2c_read_ack() has the same flaw (noted with a / TODO check / comment since the code was introduced).

Fix both functions by using a single combined check (idx + num_bytes > curlen) before each memcpy. Since num_bytes is u8, it is always >= 0, so this strictly subsumes the simpler idx > curlen form and no separate step is needed.

[added missing fixes tag]

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{
  "affected": [],
  "aliases": [
    "CVE-2026-68279"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-10T13:20:17Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/dp/mst: fix OOB reads in remote DPCD/I2C sideband reply parsers\n\ndrm_dp_sideband_parse_remote_dpcd_read() reads num_bytes from the raw\nmessage and then unconditionally does:\n\n  memcpy(bytes, \u0026raw-\u003emsg[idx], num_bytes);\n\nwithout checking that idx + num_bytes \u003c= raw-\u003ecurlen. raw-\u003emsg[] is\n256 bytes; if a malicious or misbehaving MST hub sets num_bytes larger\nthan the remaining payload, the memcpy reads past the received data\ninto whatever follows in raw-\u003emsg[].\n\ndrm_dp_sideband_parse_remote_i2c_read_ack() has the same flaw (noted\nwith a /* TODO check */ comment since the code was introduced).\n\nFix both functions by using a single combined check\n(idx + num_bytes \u003e curlen) before each memcpy. Since num_bytes is u8,\nit is always \u003e= 0, so this strictly subsumes the simpler idx \u003e curlen\nform and no separate step is needed.\n\n[added missing fixes tag]",
  "id": "GHSA-p23r-m2g4-23pq",
  "modified": "2026-08-19T18:32:12Z",
  "published": "2026-08-10T15:33:44Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-68279"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/04d953f50d61e542e94a5977822cc53735f8c0ce"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1a8f537f5a1eeac941f262fe73078d6b08ba83c0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/22d9f7fc1aaabaf73d5f30e8b0c9aa814ecd6ed2"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/533d9e2bede4aeefdc2a0561d7071cfede95958f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c2fbda0fe0163c55ba3820ee6cea0c6b43622eda"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e6ef5455b06cb4e5d181aabcd723791587c79f12"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}



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