int imap_append_message(struct Context *ctx, struct Message *msg)
{
  FILE *fp = NULL;
  char buf[LONG_STRING];
  char mbox[LONG_STRING];
  char mailbox[LONG_STRING];
  char internaldate[IMAP_DATELEN];
  char imap_flags[SHORT_STRING];
  size_t len;
  struct Progress progressbar;
  size_t sent;
  int c, last;
  struct ImapMbox mx;
  int rc;

  struct ImapData *idata = ctx->data;

  if (imap_parse_path(ctx->path, &mx))
    return -1;

  imap_fix_path(idata, mx.mbox, mailbox, sizeof(mailbox));
  if (!*mailbox)
    mutt_str_strfcpy(mailbox, "INBOX", sizeof(mailbox));

  fp = fopen(msg->path, "r");
  if (!fp)
  {
    mutt_perror(msg->path);
    goto fail;
  }

  /* currently we set the \Seen flag on all messages, but probably we
   * should scan the message Status header for flag info. Since we're
   * already rereading the whole file for length it isn't any more
   * expensive (it'd be nice if we had the file size passed in already
   * by the code that writes the file, but that's a lot of changes.
   * Ideally we'd have a Header structure with flag info here... */
  for (last = EOF, len = 0; (c = fgetc(fp)) != EOF; last = c)
  {
    if (c == '\n' && last != '\r')
      len++;

    len++;
  }
  rewind(fp);

  mutt_progress_init(&progressbar, _("Uploading message..."),
                     MUTT_PROGRESS_SIZE, NetInc, len);

  imap_munge_mbox_name(idata, mbox, sizeof(mbox), mailbox);
  mutt_date_make_imap(internaldate, sizeof(internaldate), msg->received);

  imap_flags[0] = imap_flags[1] = 0;
  if (msg->flags.read)
    mutt_str_strcat(imap_flags, sizeof(imap_flags), " \\Seen");
  if (msg->flags.replied)
    mutt_str_strcat(imap_flags, sizeof(imap_flags), " \\Answered");
  if (msg->flags.flagged)
    mutt_str_strcat(imap_flags, sizeof(imap_flags), " \\Flagged");
  if (msg->flags.draft)
    mutt_str_strcat(imap_flags, sizeof(imap_flags), " \\Draft");

  snprintf(buf, sizeof(buf), "APPEND %s (%s) \"%s\" {%lu}", mbox,
           imap_flags + 1, internaldate, (unsigned long) len);

  imap_cmd_start(idata, buf);

  do
    rc = imap_cmd_step(idata);
  while (rc == IMAP_CMD_CONTINUE);

  if (rc != IMAP_CMD_RESPOND)
  {
    mutt_debug(1, "#1 command failed: %s\n", idata->buf);

    char *pc = idata->buf + SEQLEN;
    SKIPWS(pc);
    pc = imap_next_word(pc);
    mutt_error("%s", pc);
    mutt_file_fclose(&fp);
    goto fail;
  }

  for (last = EOF, sent = len = 0; (c = fgetc(fp)) != EOF; last = c)
  {
    if (c == '\n' && last != '\r')
      buf[len++] = '\r';

    buf[len++] = c;

    if (len > sizeof(buf) - 3)
    {
      sent += len;
      flush_buffer(buf, &len, idata->conn);
      mutt_progress_update(&progressbar, sent, -1);
    }
  }

  if (len)
    flush_buffer(buf, &len, idata->conn);

  mutt_socket_send(idata->conn, "\r\n");
  mutt_file_fclose(&fp);

  do
    rc = imap_cmd_step(idata);
  while (rc == IMAP_CMD_CONTINUE);

  if (!imap_code(idata->buf))
  {
    mutt_debug(1, "#2 command failed: %s\n", idata->buf);
    char *pc = idata->buf + SEQLEN;
    SKIPWS(pc);
    pc = imap_next_word(pc);
    mutt_error("%s", pc);
    goto fail;
  }

  FREE(&mx.mbox);
  return 0;

fail:
  FREE(&mx.mbox);
  return -1;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.