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CVE-2026-68278

Status: ReceivedUnscored—

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

drm/dp/mst: fix buffer overflows in sideband chunk accumulation

drm_dp_sideband_append_payload() has three related bugs when processing device-provided sideband reply data:

All three are reachable from any DP MST device that can forge sideband reply messages on a physical connection.

Technical details traces, logs and code from the original report
1. Zero-length curchunk_len underflow: msg_len is a 6-bit field taken
   directly from the DP sideband header. If a device sends msg_len=0,
   curchunk_len is set to zero. The condition (curchunk_idx >= curchunk_len)
   is immediately true, and curchunk_len-1 wraps to 255 (u8 underflow).
   drm_dp_msg_data_crc4() reads 255 bytes from chunk[48], then memcpy()
   writes 255 bytes into msg[], both far out of bounds.

2. chunk[48] overflow: curchunk_len can reach 63 (6-bit field). chunk[] is
   only 48 bytes. Multi-iteration payload assembly appends 16-byte blocks
   until curchunk_idx reaches curchunk_len, writing up to 15 bytes past
   the end of chunk[] into msg[].

3. msg[256] overflow: each chunk contributes (curchunk_len-1) bytes to
   msg[]. No check ensures curlen + (curchunk_len-1) stays within msg[256],
   so the memcpy can spill into adjacent struct fields.

CVSS

NVD hasn't assigned a CVSS score to this CVE (common since the April 2026 policy change).

Exploitation probability (EPSS)

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

Affected technologies (1)

⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.

Linux — Linux KernelAI

References

Raw JSON (NVD)

Show
{
  "id": "CVE-2026-68278",
  "cveTags": [],
  "metrics": {},
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "ad7f8a1f9ced7f049f9b66d588723f243a7034cd",
              "lessThan": "ef2ecb6cf268debf3890df99fea01b6452dcf78e",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "ad7f8a1f9ced7f049f9b66d588723f243a7034cd",
              "lessThan": "d4e05dedb252ed3e540a0c9be511e427f098110a",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "ad7f8a1f9ced7f049f9b66d588723f243a7034cd",
              "lessThan": "4d5109075a787de28c9e89940f9dee45269f91fa",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "ad7f8a1f9ced7f049f9b66d588723f243a7034cd",
              "lessThan": "53937a2787d29c7a460e984dc4f20ff6ac91dc65",
              "versionType": "git"
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            {
              "status": "affected",
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              "versionType": "git"
            },
            {
              "status": "affected",
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            {
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              "versionType": "git"
            }
          ],
          "programFiles": [
            "drivers/gpu/drm/display/drm_dp_mst_topology.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3.17"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "3.17",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "5.10.266",
              "versionType": "semver",
              "lessThanOrEqual": "5.10.*"
            },
            {
              "status": "unaffected",
              "version": "5.15.217",
              "versionType": "semver",
              "lessThanOrEqual": "5.15.*"
            },
            {
              "status": "unaffected",
              "version": "6.1.183",
              "versionType": "semver",
              "lessThanOrEqual": "6.1.*"
            },
            {
              "status": "unaffected",
              "version": "6.6.148",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "status": "unaffected",
              "version": "6.12.101",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.18.42",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.1.6",
              "versionType": "semver",
              "lessThanOrEqual": "7.1.*"
            },
            {
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "drivers/gpu/drm/display/drm_dp_mst_topology.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-08-10T13:20:16.920",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/1e5827839ad0ceb0079d1560c321fa3656b54f21",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/4d5109075a787de28c9e89940f9dee45269f91fa",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/53937a2787d29c7a460e984dc4f20ff6ac91dc65",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/55bd5e685bda455b9b50c835f8c8442d52a344a3",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/a6366b551079c79bf7bdbadd74c97358bcfe2d58",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/d4e05dedb252ed3e540a0c9be511e427f098110a",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/ef0dbcc200c3389f1f781ab181932a97e54b51af",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/ef2ecb6cf268debf3890df99fea01b6452dcf78e",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/dp/mst: fix buffer overflows in sideband chunk accumulation\n\ndrm_dp_sideband_append_payload() has three related bugs when processing\ndevice-provided sideband reply data:\n\n1. Zero-length curchunk_len underflow: msg_len is a 6-bit field taken\n   directly from the DP sideband header. If a device sends msg_len=0,\n   curchunk_len is set to zero. The condition (curchunk_idx >= curchunk_len)\n   is immediately true, and curchunk_len-1 wraps to 255 (u8 underflow).\n   drm_dp_msg_data_crc4() reads 255 bytes from chunk[48], then memcpy()\n   writes 255 bytes into msg[], both far out of bounds.\n\n2. chunk[48] overflow: curchunk_len can reach 63 (6-bit field). chunk[] is\n   only 48 bytes. Multi-iteration payload assembly appends 16-byte blocks\n   until curchunk_idx reaches curchunk_len, writing up to 15 bytes past\n   the end of chunk[] into msg[].\n\n3. msg[256] overflow: each chunk contributes (curchunk_len-1) bytes to\n   msg[]. No check ensures curlen + (curchunk_len-1) stays within msg[256],\n   so the memcpy can spill into adjacent struct fields.\n\nAll three are reachable from any DP MST device that can forge sideband\nreply messages on a physical connection."
    }
  ],
  "lastModified": "2026-08-23T13:16:36.020",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}