Bluetooth: L2CAP: ecred_reconfigure: send packed pdu, not stack pointer

{
  "id": "4213631a6dd27a501d4649aa0e8c5024b95ceb523f5033550148247eae3116ce",
  "url": "https://osv.dev/vulnerability/CVE-2026-64127",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Bluetooth: L2CAP: ecred_reconfigure: send packed pdu, not stack pointer",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: ecred_reconfigure: send packed pdu, not stack pointer Commit 1c08108f3014 (\"Bluetooth: L2CAP: Avoid -Wflex-array-member-not-at-end warnings\") converted the on-stack request PDU in l2cap_ecred_reconfigure() from an explicit packed struct to DEFINE_RAW_FLEX(), but did not adjust the size and source-pointer arguments to l2cap_send_cmd(): - struct { - struct l2cap_ecred_reconf_req req; - __le16 scid; - } pdu; + DEFINE_RAW_FLEX(struct l2cap_ecred_reconf_req, pdu, scid, 1); ... l2cap_send_cmd(conn, chan->ident, L2CAP_ECRED_RECONF_REQ, sizeof(pdu), &pdu); After the conversion, DEFINE_RAW_FLEX() expands to declare an anonymous union pdu_u plus a local pointer \"pdu\" pointing at it. Therefore: - sizeof(pdu) is now sizeof(struct l2cap_ecred_reconf_req *) = 8 on 64-bit (4 on 32-bit), not the 6 bytes of (mtu, mps, scid[1]). - &pdu is the address of the local pointer's stack storage, not the address of the request payload. l2cap_send_cmd() forwards (data, count) to l2cap_build_cmd(), which calls skb_put_data(skb, data, count). The L2CAP_ECRED_RECONFIGURE_REQ packet body therefore contains 8 bytes copied from the kernel stack starting at &pdu -- the 8 bytes overlap the pdu pointer's value, leaking a kernel stack address to the paired Bluetooth peer. The intended (mtu, mps, scid) fields are not transmitted at all, so the peer rejects the request as malformed and the L2CAP_ECRED_RECONFIGURE feature itself ha",
    "evidence": "osv:CVE-2026-64127",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.12.92",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.34",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.0.11",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-64127",
      "aliases": [
        "CVE-2026-64127"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "1c08108f3014881ad5f4c35a2abaf9c65475035d"
                },
                {
                  "fixed": "ed5fcd2a26f0c16fc289c8cd6b03328a0582a687"
                },
                {
                  "fixed": "051922ab709c0a6917eae765c22481dfc68379e5"
                },
                {
                  "fixed": "356c9d1a1cbacd2a1640fff3c050e1c3472e924f"
                },
                {
                  "fixed": "3374ef8cf99368a40f7efd51a2a375a4c5dc6f0d"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64127.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.10.0"
                },
                {
                  "fixed": "6.12.92"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.18.34"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.0.11"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64127.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:39.907722097Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/051922ab709c0a6917eae765c22481dfc68379e5",
        "https://git.kernel.org/stable/c/3374ef8cf99368a40f7efd51a2a375a4c5dc6f0d",
        "https://git.kernel.org/stable/c/356c9d1a1cbacd2a1640fff3c050e1c3472e924f",
        "https://git.kernel.org/stable/c/ed5fcd2a26f0c16fc289c8cd6b03328a0582a687",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64127.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-64127",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64127.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-64127",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 507402,
  "published_at": "2026-07-19T15:40:23.96+00:00"
}