{
  "affected": [
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:12",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:13",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.12.85-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:14",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7.0.3-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "In the Linux kernel, the following vulnerability has been resolved:  ksmbd: validate response sizes in ipc_validate_msg()  ipc_validate_msg() computes the expected message size for each response type by adding (or multiplying) attacker-controlled fields from the daemon response to a fixed struct size in unsigned int arithmetic.  Three cases can overflow:    KSMBD_EVENT_RPC_REQUEST:       msg_sz = sizeof(struct ksmbd_rpc_command) + resp-\u003epayload_sz;   KSMBD_EVENT_SHARE_CONFIG_REQUEST:       msg_sz = sizeof(struct ksmbd_share_config_response) +                resp-\u003epayload_sz;   KSMBD_EVENT_LOGIN_REQUEST_EXT:       msg_sz = sizeof(struct ksmbd_login_response_ext) +                resp-\u003engroups * sizeof(gid_t);  resp-\u003epayload_sz is __u32 and resp-\u003engroups is __s32.  Each addition can wrap in unsigned int; the multiplication by sizeof(gid_t) mixes signed and size_t, so a negative ngroups is converted to SIZE_MAX before the multiply.  A wrapped value of msg_sz that happens to equal entry-\u003emsg_sz bypasses the size check on the next line, and downstream consumers (smb2pdu.c:6742 memcpy using rpc_resp-\u003epayload_sz, kmemdup in ksmbd_alloc_user using resp_ext-\u003engroups) then trust the unverified length.  Use check_add_overflow() on the RPC_REQUEST and SHARE_CONFIG_REQUEST paths to detect integer overflow without constraining functional payload size; userspace ksmbd-tools grows NDR responses in 4096-byte chunks for calls like NetShareEnumAll, so a hard transport cap is unworkable on the response side.  For LOGIN_REQUEST_EXT, reject resp-\u003engroups outside the signed [0, NGROUPS_MAX] range up front and report the error from ipc_validate_msg() so it fires at the IPC boundary; with that bound the subsequent multiplication and addition stay well below UINT_MAX.  The now-redundant ngroups check and pr_err in ksmbd_alloc_user() are removed.  This is the response-side analogue of aab98e2dbd64 (\"ksmbd: fix integer overflows on 32 bit systems\"), which hardened the request side.",
  "id": "DEBIAN-CVE-2026-31707",
  "modified": "2026-05-09T22:47:55.673625770Z",
  "published": "2026-05-01T14:16:20.720Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://security-tracker.debian.org/tracker/CVE-2026-31707"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "upstream": [
    "CVE-2026-31707"
  ]
}